diff --git a/browser/actors/AboutNewTabChild.sys.mjs b/browser/actors/AboutNewTabChild.sys.mjs
index 7bb0433b050e..1595e8c8f2ee 100644
--- a/browser/actors/AboutNewTabChild.sys.mjs
+++ b/browser/actors/AboutNewTabChild.sys.mjs
@@ -2,7 +2,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
diff --git a/browser/actors/AboutNewTabParent.sys.mjs b/browser/actors/AboutNewTabParent.sys.mjs
index ccbae0a357a9..479ea95b1c0a 100644
--- a/browser/actors/AboutNewTabParent.sys.mjs
+++ b/browser/actors/AboutNewTabParent.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/actors/AboutPluginsParent.sys.mjs b/browser/actors/AboutPluginsParent.sys.mjs
index a178fd3a5311..735782868d89 100644
--- a/browser/actors/AboutPluginsParent.sys.mjs
+++ b/browser/actors/AboutPluginsParent.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const lazy = {};
 
 ChromeUtils.defineModuleGetter(
diff --git a/browser/actors/AboutReaderChild.sys.mjs b/browser/actors/AboutReaderChild.sys.mjs
index ca4ecdb038e6..728b098a0e32 100644
--- a/browser/actors/AboutReaderChild.sys.mjs
+++ b/browser/actors/AboutReaderChild.sys.mjs
@@ -2,7 +2,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 const lazy = {};
 
diff --git a/browser/actors/AboutReaderParent.sys.mjs b/browser/actors/AboutReaderParent.sys.mjs
index 4a10ba665e0f..d8969262a55e 100644
--- a/browser/actors/AboutReaderParent.sys.mjs
+++ b/browser/actors/AboutReaderParent.sys.mjs
@@ -3,8 +3,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const lazy = {};
 
 ChromeUtils.defineESModuleGetters(lazy, {
diff --git a/browser/actors/AboutTabCrashedParent.sys.mjs b/browser/actors/AboutTabCrashedParent.sys.mjs
index 95032d5380b3..9cea8f240c5e 100644
--- a/browser/actors/AboutTabCrashedParent.sys.mjs
+++ b/browser/actors/AboutTabCrashedParent.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/actors/BrowserProcessChild.sys.mjs b/browser/actors/BrowserProcessChild.sys.mjs
index f0f8dee9132a..1a9e0d284ca0 100644
--- a/browser/actors/BrowserProcessChild.sys.mjs
+++ b/browser/actors/BrowserProcessChild.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const lazy = {};
 
 ChromeUtils.defineModuleGetter(
diff --git a/browser/actors/BrowserTabChild.sys.mjs b/browser/actors/BrowserTabChild.sys.mjs
index 09f72f2c1bbd..c56f56d27d04 100644
--- a/browser/actors/BrowserTabChild.sys.mjs
+++ b/browser/actors/BrowserTabChild.sys.mjs
@@ -2,7 +2,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 const lazy = {};
 
diff --git a/browser/actors/BrowserTabParent.sys.mjs b/browser/actors/BrowserTabParent.sys.mjs
index 1183899055e9..6915fea8e988 100644
--- a/browser/actors/BrowserTabParent.sys.mjs
+++ b/browser/actors/BrowserTabParent.sys.mjs
@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 const { BrowserWindowTracker } = ChromeUtils.import(
   "resource:///modules/BrowserWindowTracker.jsm"
diff --git a/browser/actors/ContentSearchChild.sys.mjs b/browser/actors/ContentSearchChild.sys.mjs
index a58352177e04..79cca36bae31 100644
--- a/browser/actors/ContentSearchChild.sys.mjs
+++ b/browser/actors/ContentSearchChild.sys.mjs
@@ -2,7 +2,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 export class ContentSearchChild extends JSWindowActorChild {
   handleEvent(event) {
diff --git a/browser/actors/ContentSearchParent.sys.mjs b/browser/actors/ContentSearchParent.sys.mjs
index b8b039aba4b3..00b9c0939d59 100644
--- a/browser/actors/ContentSearchParent.sys.mjs
+++ b/browser/actors/ContentSearchParent.sys.mjs
@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
diff --git a/browser/actors/FormValidationChild.sys.mjs b/browser/actors/FormValidationChild.sys.mjs
index 7e18509de79c..33a59552063f 100644
--- a/browser/actors/FormValidationChild.sys.mjs
+++ b/browser/actors/FormValidationChild.sys.mjs
@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 /**
  * Handles the validation callback from nsIFormFillController and
diff --git a/browser/actors/FormValidationParent.sys.mjs b/browser/actors/FormValidationParent.sys.mjs
index 98c3a13f7697..a636c60f34bf 100644
--- a/browser/actors/FormValidationParent.sys.mjs
+++ b/browser/actors/FormValidationParent.sys.mjs
@@ -6,8 +6,6 @@
  * Chrome side handling of form validation popup.
  */
 
-"use strict";
-
 const lazy = {};
 
 ChromeUtils.defineModuleGetter(
diff --git a/browser/actors/ScreenshotsComponentChild.sys.mjs b/browser/actors/ScreenshotsComponentChild.sys.mjs
index d5e92e3b4a53..2932068954d8 100644
--- a/browser/actors/ScreenshotsComponentChild.sys.mjs
+++ b/browser/actors/ScreenshotsComponentChild.sys.mjs
@@ -3,8 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 /* eslint-env mozilla/browser-window */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/enterprisepolicies/Policies.sys.mjs b/browser/components/enterprisepolicies/Policies.sys.mjs
index cb7bde51788a..7c5212d4d717 100644
--- a/browser/components/enterprisepolicies/Policies.sys.mjs
+++ b/browser/components/enterprisepolicies/Policies.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const { AppConstants } = ChromeUtils.import(
diff --git a/browser/components/enterprisepolicies/helpers/BookmarksPolicies.sys.mjs b/browser/components/enterprisepolicies/helpers/BookmarksPolicies.sys.mjs
index 627e03a23003..f1ae9d0a30a9 100644
--- a/browser/components/enterprisepolicies/helpers/BookmarksPolicies.sys.mjs
+++ b/browser/components/enterprisepolicies/helpers/BookmarksPolicies.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /*
  * A Bookmark object received through the policy engine will be an
  * object with the following properties:
diff --git a/browser/components/enterprisepolicies/helpers/ProxyPolicies.sys.mjs b/browser/components/enterprisepolicies/helpers/ProxyPolicies.sys.mjs
index b351978c721f..516230c8a723 100644
--- a/browser/components/enterprisepolicies/helpers/ProxyPolicies.sys.mjs
+++ b/browser/components/enterprisepolicies/helpers/ProxyPolicies.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const PREF_LOGLEVEL = "browser.policies.loglevel";
diff --git a/browser/components/enterprisepolicies/helpers/WebsiteFilter.sys.mjs b/browser/components/enterprisepolicies/helpers/WebsiteFilter.sys.mjs
index 061a12e55d4a..a1aa03a33eab 100644
--- a/browser/components/enterprisepolicies/helpers/WebsiteFilter.sys.mjs
+++ b/browser/components/enterprisepolicies/helpers/WebsiteFilter.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /*
  * This module implements the policy to block websites from being visited,
  * or to only allow certain websites to be visited.
diff --git a/browser/components/firefoxview/colorways-card.mjs b/browser/components/firefoxview/colorways-card.mjs
index 3e22eb1bbb35..97f567067be7 100644
--- a/browser/components/firefoxview/colorways-card.mjs
+++ b/browser/components/firefoxview/colorways-card.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const { BuiltInThemes } = ChromeUtils.import(
   "resource:///modules/BuiltInThemes.jsm"
 );
diff --git a/browser/components/firefoxview/featureCallout.mjs b/browser/components/firefoxview/featureCallout.mjs
index 31a37a711f76..6620459cee6c 100644
--- a/browser/components/firefoxview/featureCallout.mjs
+++ b/browser/components/firefoxview/featureCallout.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
diff --git a/browser/components/firefoxview/firefox-view-notification-manager.sys.mjs b/browser/components/firefoxview/firefox-view-notification-manager.sys.mjs
index 8b398800b253..22f79eb4a58a 100644
--- a/browser/components/firefoxview/firefox-view-notification-manager.sys.mjs
+++ b/browser/components/firefoxview/firefox-view-notification-manager.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports the FirefoxViewNotificationManager singleton, which manages the notification state
  * for the Firefox View button
diff --git a/browser/components/firefoxview/firefox-view-tabs-setup-manager.sys.mjs b/browser/components/firefoxview/firefox-view-tabs-setup-manager.sys.mjs
index 6b4096990447..17c3da5e7098 100644
--- a/browser/components/firefoxview/firefox-view-tabs-setup-manager.sys.mjs
+++ b/browser/components/firefoxview/firefox-view-tabs-setup-manager.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports the TabsSetupFlowManager singleton, which manages the state and
  * diverse inputs which drive the Firefox View synced tabs setup flow
diff --git a/browser/components/firefoxview/firefoxview.mjs b/browser/components/firefoxview/firefoxview.mjs
index 9cdc4c210d40..9e47c1eb8d2b 100644
--- a/browser/components/firefoxview/firefoxview.mjs
+++ b/browser/components/firefoxview/firefoxview.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 window.addEventListener("DOMContentLoaded", () => {
   Services.telemetry.setEventRecordingEnabled("firefoxview", true);
   Services.telemetry.recordEvent("firefoxview", "entered", "firefoxview", null);
diff --git a/browser/components/firefoxview/recently-closed-tabs.mjs b/browser/components/firefoxview/recently-closed-tabs.mjs
index 4b194ff452ce..6ba6b169d5c7 100644
--- a/browser/components/firefoxview/recently-closed-tabs.mjs
+++ b/browser/components/firefoxview/recently-closed-tabs.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const lazy = {};
 ChromeUtils.defineModuleGetter(
   lazy,
diff --git a/browser/components/firefoxview/tab-pickup-list.mjs b/browser/components/firefoxview/tab-pickup-list.mjs
index 86d0c74df735..cc7598ab6197 100644
--- a/browser/components/firefoxview/tab-pickup-list.mjs
+++ b/browser/components/firefoxview/tab-pickup-list.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const lazy = {};
 ChromeUtils.defineModuleGetter(
   lazy,
diff --git a/browser/components/pagedata/OpenGraphPageData.sys.mjs b/browser/components/pagedata/OpenGraphPageData.sys.mjs
index 736e7588892f..8f8b361799f3 100644
--- a/browser/components/pagedata/OpenGraphPageData.sys.mjs
+++ b/browser/components/pagedata/OpenGraphPageData.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * Collects Open Graph (https://opengraphprotocol.org/) related data from a page.
  */
diff --git a/browser/components/pagedata/PageDataChild.sys.mjs b/browser/components/pagedata/PageDataChild.sys.mjs
index 300b37d53283..5fff89db1684 100644
--- a/browser/components/pagedata/PageDataChild.sys.mjs
+++ b/browser/components/pagedata/PageDataChild.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/pagedata/PageDataParent.sys.mjs b/browser/components/pagedata/PageDataParent.sys.mjs
index ad3d10b8725e..d9943c8854c6 100644
--- a/browser/components/pagedata/PageDataParent.sys.mjs
+++ b/browser/components/pagedata/PageDataParent.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/pagedata/PageDataSchema.sys.mjs b/browser/components/pagedata/PageDataSchema.sys.mjs
index df09fd18304a..14eb681cccfe 100644
--- a/browser/components/pagedata/PageDataSchema.sys.mjs
+++ b/browser/components/pagedata/PageDataSchema.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/pagedata/PageDataService.sys.mjs b/browser/components/pagedata/PageDataService.sys.mjs
index ddd36170dc68..c629e4736bce 100644
--- a/browser/components/pagedata/PageDataService.sys.mjs
+++ b/browser/components/pagedata/PageDataService.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const { EventEmitter } = ChromeUtils.import(
diff --git a/browser/components/pagedata/SchemaOrgPageData.sys.mjs b/browser/components/pagedata/SchemaOrgPageData.sys.mjs
index 92e46cb6c29f..1c3e965ba914 100644
--- a/browser/components/pagedata/SchemaOrgPageData.sys.mjs
+++ b/browser/components/pagedata/SchemaOrgPageData.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { PageDataSchema } from "resource:///modules/pagedata/PageDataSchema.sys.mjs";
 
 /**
diff --git a/browser/components/pagedata/TwitterPageData.sys.mjs b/browser/components/pagedata/TwitterPageData.sys.mjs
index e6ee721a70de..88b06098cb40 100644
--- a/browser/components/pagedata/TwitterPageData.sys.mjs
+++ b/browser/components/pagedata/TwitterPageData.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * Collects Twitter card (https://developer.twitter.com/en/docs/twitter-for-websites/)
  * related data from a page.
diff --git a/browser/components/places/CommonNames.sys.mjs b/browser/components/places/CommonNames.sys.mjs
index ed797d5faab2..600968a40377 100644
--- a/browser/components/places/CommonNames.sys.mjs
+++ b/browser/components/places/CommonNames.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
diff --git a/browser/components/places/Interactions.sys.mjs b/browser/components/places/Interactions.sys.mjs
index da47572b4fd0..4d2d0d68056d 100644
--- a/browser/components/places/Interactions.sys.mjs
+++ b/browser/components/places/Interactions.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/places/InteractionsBlocklist.sys.mjs b/browser/components/places/InteractionsBlocklist.sys.mjs
index 7a9941f489a7..770d15b0bb1a 100644
--- a/browser/components/places/InteractionsBlocklist.sys.mjs
+++ b/browser/components/places/InteractionsBlocklist.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/places/InteractionsChild.sys.mjs b/browser/components/places/InteractionsChild.sys.mjs
index 47794dc9490e..db6f49f83b3f 100644
--- a/browser/components/places/InteractionsChild.sys.mjs
+++ b/browser/components/places/InteractionsChild.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const lazy = {};
 
 ChromeUtils.defineModuleGetter(
diff --git a/browser/components/places/InteractionsParent.sys.mjs b/browser/components/places/InteractionsParent.sys.mjs
index 3dc2d1e176f7..a43774ef97e6 100644
--- a/browser/components/places/InteractionsParent.sys.mjs
+++ b/browser/components/places/InteractionsParent.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const lazy = {};
 
 ChromeUtils.defineESModuleGetters(lazy, {
diff --git a/browser/components/places/SnapshotGroups.sys.mjs b/browser/components/places/SnapshotGroups.sys.mjs
index ec3387fbcb43..18088cbe31a7 100644
--- a/browser/components/places/SnapshotGroups.sys.mjs
+++ b/browser/components/places/SnapshotGroups.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/places/Snapshots.sys.mjs b/browser/components/places/Snapshots.sys.mjs
index 8e108fc6c7a7..cae9de6acca6 100644
--- a/browser/components/places/Snapshots.sys.mjs
+++ b/browser/components/places/Snapshots.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/screenshots/ScreenshotsUtils.sys.mjs b/browser/components/screenshots/ScreenshotsUtils.sys.mjs
index 6b7097df4be6..31f830258a9d 100644
--- a/browser/components/screenshots/ScreenshotsUtils.sys.mjs
+++ b/browser/components/screenshots/ScreenshotsUtils.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/search/BrowserSearchTelemetry.sys.mjs b/browser/components/search/BrowserSearchTelemetry.sys.mjs
index e946591e2cfa..51cadc5505dd 100644
--- a/browser/components/search/BrowserSearchTelemetry.sys.mjs
+++ b/browser/components/search/BrowserSearchTelemetry.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/search/SearchOneOffs.sys.mjs b/browser/components/search/SearchOneOffs.sys.mjs
index 6eda01009de9..8d3c7edfc15d 100644
--- a/browser/components/search/SearchOneOffs.sys.mjs
+++ b/browser/components/search/SearchOneOffs.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/search/SearchSERPTelemetry.sys.mjs b/browser/components/search/SearchSERPTelemetry.sys.mjs
index 0c130f91cb90..4b1d814b1a17 100644
--- a/browser/components/search/SearchSERPTelemetry.sys.mjs
+++ b/browser/components/search/SearchSERPTelemetry.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/search/SearchUIUtils.sys.mjs b/browser/components/search/SearchUIUtils.sys.mjs
index b9d00eceb240..7469e79ac5c2 100644
--- a/browser/components/search/SearchUIUtils.sys.mjs
+++ b/browser/components/search/SearchUIUtils.sys.mjs
@@ -6,8 +6,6 @@
  * Various utilities for search related UI.
  */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/urlbar/QuickActionsLoaderDefault.sys.mjs b/browser/components/urlbar/QuickActionsLoaderDefault.sys.mjs
index 8ad545e0cc55..704866c4bf07 100644
--- a/browser/components/urlbar/QuickActionsLoaderDefault.sys.mjs
+++ b/browser/components/urlbar/QuickActionsLoaderDefault.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/urlbar/UrlbarController.sys.mjs b/browser/components/urlbar/UrlbarController.sys.mjs
index 5325e7641f79..bd8db396cf87 100644
--- a/browser/components/urlbar/UrlbarController.sys.mjs
+++ b/browser/components/urlbar/UrlbarController.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const { AppConstants } = ChromeUtils.import(
diff --git a/browser/components/urlbar/UrlbarEventBufferer.sys.mjs b/browser/components/urlbar/UrlbarEventBufferer.sys.mjs
index 1c23b74f88c7..39c70ab54f55 100644
--- a/browser/components/urlbar/UrlbarEventBufferer.sys.mjs
+++ b/browser/components/urlbar/UrlbarEventBufferer.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const { AppConstants } = ChromeUtils.import(
diff --git a/browser/components/urlbar/UrlbarInput.sys.mjs b/browser/components/urlbar/UrlbarInput.sys.mjs
index f6febb5d16a3..adbaeb27efa5 100644
--- a/browser/components/urlbar/UrlbarInput.sys.mjs
+++ b/browser/components/urlbar/UrlbarInput.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const { AppConstants } = ChromeUtils.import(
diff --git a/browser/components/urlbar/UrlbarMuxerUnifiedComplete.sys.mjs b/browser/components/urlbar/UrlbarMuxerUnifiedComplete.sys.mjs
index a04521e70bdb..1f205e8e6ece 100644
--- a/browser/components/urlbar/UrlbarMuxerUnifiedComplete.sys.mjs
+++ b/browser/components/urlbar/UrlbarMuxerUnifiedComplete.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a component used to sort results in a UrlbarQueryContext.
  */
diff --git a/browser/components/urlbar/UrlbarPrefs.sys.mjs b/browser/components/urlbar/UrlbarPrefs.sys.mjs
index d2dd0d7c5b84..f4e9101b739f 100644
--- a/browser/components/urlbar/UrlbarPrefs.sys.mjs
+++ b/browser/components/urlbar/UrlbarPrefs.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports the UrlbarPrefs singleton, which manages preferences for
  * the urlbar. It also provides access to urlbar Nimbus variables as if they are
diff --git a/browser/components/urlbar/UrlbarProviderAboutPages.sys.mjs b/browser/components/urlbar/UrlbarProviderAboutPages.sys.mjs
index 64c19e6185cd..78f95a1fd25c 100644
--- a/browser/components/urlbar/UrlbarProviderAboutPages.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderAboutPages.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that offers about pages.
  */
diff --git a/browser/components/urlbar/UrlbarProviderAliasEngines.sys.mjs b/browser/components/urlbar/UrlbarProviderAliasEngines.sys.mjs
index c4a0f9ff75a6..9785e26adadf 100644
--- a/browser/components/urlbar/UrlbarProviderAliasEngines.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderAliasEngines.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that offers engines with aliases as heuristic
  * results.
diff --git a/browser/components/urlbar/UrlbarProviderAutofill.sys.mjs b/browser/components/urlbar/UrlbarProviderAutofill.sys.mjs
index b139ade4db50..78da6d97d7e0 100644
--- a/browser/components/urlbar/UrlbarProviderAutofill.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderAutofill.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that provides an autofill result.
  */
diff --git a/browser/components/urlbar/UrlbarProviderBookmarkKeywords.sys.mjs b/browser/components/urlbar/UrlbarProviderBookmarkKeywords.sys.mjs
index 1bef1c0f6511..a4d7dbbff14f 100644
--- a/browser/components/urlbar/UrlbarProviderBookmarkKeywords.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderBookmarkKeywords.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that offers bookmarks with keywords.
  */
diff --git a/browser/components/urlbar/UrlbarProviderCalculator.sys.mjs b/browser/components/urlbar/UrlbarProviderCalculator.sys.mjs
index dd82c7b8bd46..e3bcf1436540 100644
--- a/browser/components/urlbar/UrlbarProviderCalculator.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderCalculator.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 import {
diff --git a/browser/components/urlbar/UrlbarProviderExtension.sys.mjs b/browser/components/urlbar/UrlbarProviderExtension.sys.mjs
index 86c27ca83eb0..dc2e5830f29c 100644
--- a/browser/components/urlbar/UrlbarProviderExtension.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderExtension.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider class that is used for providers created by
  * extensions.
diff --git a/browser/components/urlbar/UrlbarProviderHeuristicFallback.sys.mjs b/browser/components/urlbar/UrlbarProviderHeuristicFallback.sys.mjs
index 97af6285c6d1..3298434bb9c3 100644
--- a/browser/components/urlbar/UrlbarProviderHeuristicFallback.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderHeuristicFallback.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that provides a heuristic result. The result
  * either vists a URL or does a search with the current engine. This result is
diff --git a/browser/components/urlbar/UrlbarProviderInputHistory.sys.mjs b/browser/components/urlbar/UrlbarProviderInputHistory.sys.mjs
index 7a7a23b8e727..9451efd41ada 100644
--- a/browser/components/urlbar/UrlbarProviderInputHistory.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderInputHistory.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that offers input history (aka adaptive
  * history) results. These results map typed search strings to Urlbar results.
diff --git a/browser/components/urlbar/UrlbarProviderInterventions.sys.mjs b/browser/components/urlbar/UrlbarProviderInterventions.sys.mjs
index 575205158bb8..a77dd5445eff 100644
--- a/browser/components/urlbar/UrlbarProviderInterventions.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderInterventions.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 import {
diff --git a/browser/components/urlbar/UrlbarProviderOmnibox.sys.mjs b/browser/components/urlbar/UrlbarProviderOmnibox.sys.mjs
index 64b86bea51b2..f6a4b22bfe8b 100644
--- a/browser/components/urlbar/UrlbarProviderOmnibox.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderOmnibox.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider class that is used for providers created by
  * extensions using the `omnibox` API.
diff --git a/browser/components/urlbar/UrlbarProviderOpenTabs.sys.mjs b/browser/components/urlbar/UrlbarProviderOpenTabs.sys.mjs
index 7626d12cf4b8..818421a1b17c 100644
--- a/browser/components/urlbar/UrlbarProviderOpenTabs.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderOpenTabs.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider, returning open tabs matches for the urlbar.
  * It is also used to register and unregister open tabs.
diff --git a/browser/components/urlbar/UrlbarProviderPlaces.sys.mjs b/browser/components/urlbar/UrlbarProviderPlaces.sys.mjs
index 451bc32f76ea..ebcd059a5208 100644
--- a/browser/components/urlbar/UrlbarProviderPlaces.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderPlaces.sys.mjs
@@ -5,8 +5,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 /* eslint complexity: ["error", 53] */
 
-"use strict";
-
 /**
  * This module exports a provider that provides results from the Places
  * database, including history, bookmarks, and open tabs.
diff --git a/browser/components/urlbar/UrlbarProviderPreloadedSites.sys.mjs b/browser/components/urlbar/UrlbarProviderPreloadedSites.sys.mjs
index beed1a209c8d..7481a673585d 100644
--- a/browser/components/urlbar/UrlbarProviderPreloadedSites.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderPreloadedSites.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that provides preloaded site results. These
  * are intended to populate address bar results when the user has no history.
diff --git a/browser/components/urlbar/UrlbarProviderPrivateSearch.sys.mjs b/browser/components/urlbar/UrlbarProviderPrivateSearch.sys.mjs
index cb73aa56954f..19696c8a6ecd 100644
--- a/browser/components/urlbar/UrlbarProviderPrivateSearch.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderPrivateSearch.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider returning a private search entry.
  */
diff --git a/browser/components/urlbar/UrlbarProviderQuickActions.sys.mjs b/browser/components/urlbar/UrlbarProviderQuickActions.sys.mjs
index 4d44908af8d4..54414dd91f18 100644
--- a/browser/components/urlbar/UrlbarProviderQuickActions.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderQuickActions.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import {
   UrlbarProvider,
   UrlbarUtils,
diff --git a/browser/components/urlbar/UrlbarProviderQuickSuggest.sys.mjs b/browser/components/urlbar/UrlbarProviderQuickSuggest.sys.mjs
index 2dc7a549cc93..3dcea5465975 100644
--- a/browser/components/urlbar/UrlbarProviderQuickSuggest.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderQuickSuggest.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 import {
diff --git a/browser/components/urlbar/UrlbarProviderRemoteTabs.sys.mjs b/browser/components/urlbar/UrlbarProviderRemoteTabs.sys.mjs
index 9e96ff0c2332..d828c294fbb9 100644
--- a/browser/components/urlbar/UrlbarProviderRemoteTabs.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderRemoteTabs.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that offers remote tabs.
  */
diff --git a/browser/components/urlbar/UrlbarProviderSearchSuggestions.sys.mjs b/browser/components/urlbar/UrlbarProviderSearchSuggestions.sys.mjs
index 4a6b6af1bd27..111782b806cb 100644
--- a/browser/components/urlbar/UrlbarProviderSearchSuggestions.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderSearchSuggestions.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that offers search engine suggestions.
  */
diff --git a/browser/components/urlbar/UrlbarProviderSearchTips.sys.mjs b/browser/components/urlbar/UrlbarProviderSearchTips.sys.mjs
index 19c2f766ea73..0a4c9c0d1ea6 100644
--- a/browser/components/urlbar/UrlbarProviderSearchTips.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderSearchTips.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that might show a tip when the user opens
  * the newtab or starts an organic search with their default search engine.
diff --git a/browser/components/urlbar/UrlbarProviderTabToSearch.sys.mjs b/browser/components/urlbar/UrlbarProviderTabToSearch.sys.mjs
index 44cc95ed2f33..746a30311be7 100644
--- a/browser/components/urlbar/UrlbarProviderTabToSearch.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderTabToSearch.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that offers a search engine when the user is
  * typing a search engine domain.
diff --git a/browser/components/urlbar/UrlbarProviderTokenAliasEngines.sys.mjs b/browser/components/urlbar/UrlbarProviderTokenAliasEngines.sys.mjs
index 47fd2d47656d..70d4e1c20137 100644
--- a/browser/components/urlbar/UrlbarProviderTokenAliasEngines.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderTokenAliasEngines.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a provider that offers token alias engines.
  */
diff --git a/browser/components/urlbar/UrlbarProviderTopSites.sys.mjs b/browser/components/urlbar/UrlbarProviderTopSites.sys.mjs
index d75d2e21cc0b..4a3250c801ee 100644
--- a/browser/components/urlbar/UrlbarProviderTopSites.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderTopSites.sys.mjs
@@ -6,8 +6,6 @@
  * This module exports a provider returning the user's newtab Top Sites.
  */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 import {
diff --git a/browser/components/urlbar/UrlbarProviderUnitConversion.sys.mjs b/browser/components/urlbar/UrlbarProviderUnitConversion.sys.mjs
index eb5352b64e08..b9610bb80ffc 100644
--- a/browser/components/urlbar/UrlbarProviderUnitConversion.sys.mjs
+++ b/browser/components/urlbar/UrlbarProviderUnitConversion.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * Provide unit converter.
  */
diff --git a/browser/components/urlbar/UrlbarProvidersManager.sys.mjs b/browser/components/urlbar/UrlbarProvidersManager.sys.mjs
index deb0155c9d90..c4d5a2d75014 100644
--- a/browser/components/urlbar/UrlbarProvidersManager.sys.mjs
+++ b/browser/components/urlbar/UrlbarProvidersManager.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a component used to register search providers and manage
  * the connection between such providers and a UrlbarController.
diff --git a/browser/components/urlbar/UrlbarQuickSuggest.sys.mjs b/browser/components/urlbar/UrlbarQuickSuggest.sys.mjs
index c1fab65b91a7..b2834b300008 100644
--- a/browser/components/urlbar/UrlbarQuickSuggest.sys.mjs
+++ b/browser/components/urlbar/UrlbarQuickSuggest.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const { EventEmitter } = ChromeUtils.import(
diff --git a/browser/components/urlbar/UrlbarResult.sys.mjs b/browser/components/urlbar/UrlbarResult.sys.mjs
index fbc2893ebfc3..9085e2aa1b94 100644
--- a/browser/components/urlbar/UrlbarResult.sys.mjs
+++ b/browser/components/urlbar/UrlbarResult.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a urlbar result class, each representing a single result
  * found by a provider that can be passed from the model to the view through
diff --git a/browser/components/urlbar/UrlbarSearchOneOffs.sys.mjs b/browser/components/urlbar/UrlbarSearchOneOffs.sys.mjs
index 5e9a96f5c538..9930073e1dea 100644
--- a/browser/components/urlbar/UrlbarSearchOneOffs.sys.mjs
+++ b/browser/components/urlbar/UrlbarSearchOneOffs.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const { SearchOneOffs } = ChromeUtils.importESModule(
   "resource:///modules/SearchOneOffs.sys.mjs"
 );
diff --git a/browser/components/urlbar/UrlbarSearchUtils.sys.mjs b/browser/components/urlbar/UrlbarSearchUtils.sys.mjs
index bd52dfe84330..2df4e97d1ac8 100644
--- a/browser/components/urlbar/UrlbarSearchUtils.sys.mjs
+++ b/browser/components/urlbar/UrlbarSearchUtils.sys.mjs
@@ -9,8 +9,6 @@
  * state, and an init method.  A separate object is easier.
  */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/urlbar/UrlbarTokenizer.sys.mjs b/browser/components/urlbar/UrlbarTokenizer.sys.mjs
index 5ea2c9b7acf5..fc34b6a9e1b1 100644
--- a/browser/components/urlbar/UrlbarTokenizer.sys.mjs
+++ b/browser/components/urlbar/UrlbarTokenizer.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports a tokenizer to be used by the urlbar model.
  * Emitted tokens are objects in the shape { type, value }, where type is one
diff --git a/browser/components/urlbar/UrlbarUtils.sys.mjs b/browser/components/urlbar/UrlbarUtils.sys.mjs
index 3bab49fae546..f84956ec7be5 100644
--- a/browser/components/urlbar/UrlbarUtils.sys.mjs
+++ b/browser/components/urlbar/UrlbarUtils.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module exports the UrlbarUtils singleton, which contains constants and
  * helper functions that are useful to all components of the urlbar.
diff --git a/browser/components/urlbar/UrlbarValueFormatter.sys.mjs b/browser/components/urlbar/UrlbarValueFormatter.sys.mjs
index 758ec8e3ca66..8c60c25b39ba 100644
--- a/browser/components/urlbar/UrlbarValueFormatter.sys.mjs
+++ b/browser/components/urlbar/UrlbarValueFormatter.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/urlbar/UrlbarView.sys.mjs b/browser/components/urlbar/UrlbarView.sys.mjs
index 852dc7335104..f72728689c17 100644
--- a/browser/components/urlbar/UrlbarView.sys.mjs
+++ b/browser/components/urlbar/UrlbarView.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/browser/components/urlbar/tests/UrlbarTestUtils.sys.mjs b/browser/components/urlbar/tests/UrlbarTestUtils.sys.mjs
index 7a1e3750bdc0..7737f414ed44 100644
--- a/browser/components/urlbar/tests/UrlbarTestUtils.sys.mjs
+++ b/browser/components/urlbar/tests/UrlbarTestUtils.sys.mjs
@@ -1,8 +1,6 @@
 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const { AppConstants } = ChromeUtils.import(
diff --git a/browser/components/urlbar/tests/quicksuggest/QuickSuggestTestUtils.sys.mjs b/browser/components/urlbar/tests/quicksuggest/QuickSuggestTestUtils.sys.mjs
index 878396e3cc36..81c391620aec 100644
--- a/browser/components/urlbar/tests/quicksuggest/QuickSuggestTestUtils.sys.mjs
+++ b/browser/components/urlbar/tests/quicksuggest/QuickSuggestTestUtils.sys.mjs
@@ -1,8 +1,6 @@
 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const {
diff --git a/browser/components/urlbar/unitconverters/UnitConverterSimple.sys.mjs b/browser/components/urlbar/unitconverters/UnitConverterSimple.sys.mjs
index 1ea354687bbf..c4240013fe35 100644
--- a/browser/components/urlbar/unitconverters/UnitConverterSimple.sys.mjs
+++ b/browser/components/urlbar/unitconverters/UnitConverterSimple.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 // NOTE: This units table need to be localized upon supporting multi locales
 //       since it supports en-US only.
 //       e.g. Should support plugada or funty as well for pound.
diff --git a/browser/components/urlbar/unitconverters/UnitConverterTemperature.sys.mjs b/browser/components/urlbar/unitconverters/UnitConverterTemperature.sys.mjs
index e59153841647..e75e92a58494 100644
--- a/browser/components/urlbar/unitconverters/UnitConverterTemperature.sys.mjs
+++ b/browser/components/urlbar/unitconverters/UnitConverterTemperature.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const ABSOLUTE = ["celsius", "kelvin", "fahrenheit"];
 const ALIAS = ["c", "k", "f"];
 const UNITS = [...ABSOLUTE, ...ALIAS];
diff --git a/browser/components/urlbar/unitconverters/UnitConverterTimezone.sys.mjs b/browser/components/urlbar/unitconverters/UnitConverterTimezone.sys.mjs
index f80f87ecdd51..e058342d0561 100644
--- a/browser/components/urlbar/unitconverters/UnitConverterTimezone.sys.mjs
+++ b/browser/components/urlbar/unitconverters/UnitConverterTimezone.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const TIMEZONES = {
   IDLW: -12,
   NT: -11,
diff --git a/intl/locale/LangPackMatcher.sys.mjs b/intl/locale/LangPackMatcher.sys.mjs
index 0b70b6b59fdd..861358779f0a 100644
--- a/intl/locale/LangPackMatcher.sys.mjs
+++ b/intl/locale/LangPackMatcher.sys.mjs
@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 const { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
diff --git a/intl/locale/tests/LangPackMatcherTestUtils.sys.mjs b/intl/locale/tests/LangPackMatcherTestUtils.sys.mjs
index 2803551a6713..4b18f1be134e 100644
--- a/intl/locale/tests/LangPackMatcherTestUtils.sys.mjs
+++ b/intl/locale/tests/LangPackMatcherTestUtils.sys.mjs
@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 import { LangPackMatcher } from "resource://gre/modules/LangPackMatcher.sys.mjs";
 
diff --git a/toolkit/actors/PictureInPictureChild.sys.mjs b/toolkit/actors/PictureInPictureChild.sys.mjs
index 31b9fd06c1b4..442845db5cc7 100644
--- a/toolkit/actors/PictureInPictureChild.sys.mjs
+++ b/toolkit/actors/PictureInPictureChild.sys.mjs
@@ -2,7 +2,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 const lazy = {};
 
diff --git a/toolkit/actors/TestProcessActorChild.sys.mjs b/toolkit/actors/TestProcessActorChild.sys.mjs
index 686f73e7f07a..b9631ff9d9d0 100644
--- a/toolkit/actors/TestProcessActorChild.sys.mjs
+++ b/toolkit/actors/TestProcessActorChild.sys.mjs
@@ -2,7 +2,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 export class TestProcessActorChild extends JSProcessActorChild {
   constructor() {
diff --git a/toolkit/actors/TestProcessActorParent.sys.mjs b/toolkit/actors/TestProcessActorParent.sys.mjs
index 5edaaa73f157..c86bd8ad8433 100644
--- a/toolkit/actors/TestProcessActorParent.sys.mjs
+++ b/toolkit/actors/TestProcessActorParent.sys.mjs
@@ -2,7 +2,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 export class TestProcessActorParent extends JSProcessActorParent {
   constructor() {
diff --git a/toolkit/actors/TestWindowChild.sys.mjs b/toolkit/actors/TestWindowChild.sys.mjs
index 82702f113c54..5df64c932ccf 100644
--- a/toolkit/actors/TestWindowChild.sys.mjs
+++ b/toolkit/actors/TestWindowChild.sys.mjs
@@ -2,7 +2,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 var docShellThunks = new Map();
 
diff --git a/toolkit/actors/TestWindowParent.sys.mjs b/toolkit/actors/TestWindowParent.sys.mjs
index 4886c0a95b85..d7d0c2b547f4 100644
--- a/toolkit/actors/TestWindowParent.sys.mjs
+++ b/toolkit/actors/TestWindowParent.sys.mjs
@@ -2,7 +2,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 export class TestWindowParent extends JSWindowActorParent {
   constructor() {
diff --git a/toolkit/components/enterprisepolicies/WindowsGPOParser.sys.mjs b/toolkit/components/enterprisepolicies/WindowsGPOParser.sys.mjs
index c6a84e9dff9f..8fc85fc584a4 100644
--- a/toolkit/components/enterprisepolicies/WindowsGPOParser.sys.mjs
+++ b/toolkit/components/enterprisepolicies/WindowsGPOParser.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const PREF_LOGLEVEL = "browser.policies.loglevel";
diff --git a/toolkit/components/enterprisepolicies/macOSPoliciesParser.sys.mjs b/toolkit/components/enterprisepolicies/macOSPoliciesParser.sys.mjs
index 90cc745fe7ea..ca4ef2374c6c 100644
--- a/toolkit/components/enterprisepolicies/macOSPoliciesParser.sys.mjs
+++ b/toolkit/components/enterprisepolicies/macOSPoliciesParser.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const PREF_LOGLEVEL = "browser.policies.loglevel";
diff --git a/toolkit/components/enterprisepolicies/tests/EnterprisePolicyTesting.sys.mjs b/toolkit/components/enterprisepolicies/tests/EnterprisePolicyTesting.sys.mjs
index fea2de26918e..833161b03bcc 100644
--- a/toolkit/components/enterprisepolicies/tests/EnterprisePolicyTesting.sys.mjs
+++ b/toolkit/components/enterprisepolicies/tests/EnterprisePolicyTesting.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const { Preferences } = ChromeUtils.import(
   "resource://gre/modules/Preferences.jsm"
 );
diff --git a/toolkit/components/pictureinpicture/PictureInPicture.sys.mjs b/toolkit/components/pictureinpicture/PictureInPicture.sys.mjs
index dde4a5f463cd..ecf76e15938f 100644
--- a/toolkit/components/pictureinpicture/PictureInPicture.sys.mjs
+++ b/toolkit/components/pictureinpicture/PictureInPicture.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const { AppConstants } = ChromeUtils.import(
   "resource://gre/modules/AppConstants.jsm"
 );
diff --git a/toolkit/components/pictureinpicture/PictureInPictureControls.sys.mjs b/toolkit/components/pictureinpicture/PictureInPictureControls.sys.mjs
index 2fad12be3407..566b6d4bfc7e 100644
--- a/toolkit/components/pictureinpicture/PictureInPictureControls.sys.mjs
+++ b/toolkit/components/pictureinpicture/PictureInPictureControls.sys.mjs
@@ -3,8 +3,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 // These denote which keyboard controls to show for a qualified video element.
 export const KEYBOARD_CONTROLS = {
   NONE: 0,
diff --git a/toolkit/components/places/Bookmarks.sys.mjs b/toolkit/components/places/Bookmarks.sys.mjs
index 8c00670354f6..4337b5905872 100644
--- a/toolkit/components/places/Bookmarks.sys.mjs
+++ b/toolkit/components/places/Bookmarks.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This module provides an asynchronous API for managing bookmarks.
  *
diff --git a/toolkit/components/places/ExtensionSearchHandler.sys.mjs b/toolkit/components/places/ExtensionSearchHandler.sys.mjs
index 2590a42f627a..bc252d9d593e 100644
--- a/toolkit/components/places/ExtensionSearchHandler.sys.mjs
+++ b/toolkit/components/places/ExtensionSearchHandler.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 // Used to keep track of all of the registered keywords, where each keyword is
 // mapped to a KeywordInfo instance.
 let gKeywordMap = new Map();
diff --git a/toolkit/components/places/History.sys.mjs b/toolkit/components/places/History.sys.mjs
index 64385abf245e..c49051305758 100644
--- a/toolkit/components/places/History.sys.mjs
+++ b/toolkit/components/places/History.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * Asynchronous API for managing history.
  *
diff --git a/toolkit/components/places/PlacesPreviews.sys.mjs b/toolkit/components/places/PlacesPreviews.sys.mjs
index 269ba18a9cac..aecbbfe12878 100644
--- a/toolkit/components/places/PlacesPreviews.sys.mjs
+++ b/toolkit/components/places/PlacesPreviews.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const { EventEmitter } = ChromeUtils.import(
   "resource://gre/modules/EventEmitter.jsm"
 );
diff --git a/toolkit/components/places/PlacesSyncUtils.sys.mjs b/toolkit/components/places/PlacesSyncUtils.sys.mjs
index fc90ad0b4c38..5ba65c9ad4cf 100644
--- a/toolkit/components/places/PlacesSyncUtils.sys.mjs
+++ b/toolkit/components/places/PlacesSyncUtils.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/toolkit/components/places/PlacesTransactions.sys.mjs b/toolkit/components/places/PlacesTransactions.sys.mjs
index 00b535d2b2c1..c075caf39692 100644
--- a/toolkit/components/places/PlacesTransactions.sys.mjs
+++ b/toolkit/components/places/PlacesTransactions.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * Overview
  * --------
diff --git a/toolkit/components/places/SyncedBookmarksMirror.sys.mjs b/toolkit/components/places/SyncedBookmarksMirror.sys.mjs
index 22738d513b3f..5d6bc404d57d 100644
--- a/toolkit/components/places/SyncedBookmarksMirror.sys.mjs
+++ b/toolkit/components/places/SyncedBookmarksMirror.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 /**
  * This file implements a mirror and two-way merger for synced bookmarks. The
  * mirror matches the complete tree stored on the Sync server, and stages new
diff --git a/toolkit/components/places/tests/PlacesTestUtils.sys.mjs b/toolkit/components/places/tests/PlacesTestUtils.sys.mjs
index 2f041ead656e..92124609450b 100644
--- a/toolkit/components/places/tests/PlacesTestUtils.sys.mjs
+++ b/toolkit/components/places/tests/PlacesTestUtils.sys.mjs
@@ -1,5 +1,3 @@
-"use strict";
-
 const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
diff --git a/toolkit/components/search/SearchEngineSelector.sys.mjs b/toolkit/components/search/SearchEngineSelector.sys.mjs
index d5c0c8aa407c..75586e595853 100644
--- a/toolkit/components/search/SearchEngineSelector.sys.mjs
+++ b/toolkit/components/search/SearchEngineSelector.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/toolkit/components/search/SearchStaticData.sys.mjs b/toolkit/components/search/SearchStaticData.sys.mjs
index d15d2d50e5d4..1e3513f9dea4 100644
--- a/toolkit/components/search/SearchStaticData.sys.mjs
+++ b/toolkit/components/search/SearchStaticData.sys.mjs
@@ -12,8 +12,6 @@
  * No high-level processing logic is applied here.
  */
 
-"use strict";
-
 // To update this list of known alternate domains, just cut-and-paste from
 // https://www.google.com/supported_domains
 const gGoogleDomainsSource =
diff --git a/toolkit/components/search/SearchSuggestionController.sys.mjs b/toolkit/components/search/SearchSuggestionController.sys.mjs
index 22a368aca9e3..5d636881c536 100644
--- a/toolkit/components/search/SearchSuggestionController.sys.mjs
+++ b/toolkit/components/search/SearchSuggestionController.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/toolkit/components/search/SearchUtils.sys.mjs b/toolkit/components/search/SearchUtils.sys.mjs
index a4c097d0435d..3bdd3d849e1c 100644
--- a/toolkit/components/search/SearchUtils.sys.mjs
+++ b/toolkit/components/search/SearchUtils.sys.mjs
@@ -4,8 +4,6 @@
 
 /* eslint no-shadow: error, mozilla/no-aArgs: error */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
diff --git a/toolkit/components/search/tests/SearchTestUtils.sys.mjs b/toolkit/components/search/tests/SearchTestUtils.sys.mjs
index eb649091ede3..ca9e2b7c727c 100644
--- a/toolkit/components/search/tests/SearchTestUtils.sys.mjs
+++ b/toolkit/components/search/tests/SearchTestUtils.sys.mjs
@@ -1,5 +1,3 @@
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const { MockRegistrar } = ChromeUtils.import(
diff --git a/toolkit/components/utils/SimpleServices.sys.mjs b/toolkit/components/utils/SimpleServices.sys.mjs
index e679e8b7a983..bfd81724f656 100644
--- a/toolkit/components/utils/SimpleServices.sys.mjs
+++ b/toolkit/components/utils/SimpleServices.sys.mjs
@@ -10,8 +10,6 @@
  * eagerly loaded at startup.
  */
 
-"use strict";
-
 /* globals WebExtensionPolicy */
 
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
diff --git a/toolkit/modules/IgnoreLists.sys.mjs b/toolkit/modules/IgnoreLists.sys.mjs
index 8c4f32ee9c71..d2553c915db6 100644
--- a/toolkit/modules/IgnoreLists.sys.mjs
+++ b/toolkit/modules/IgnoreLists.sys.mjs
@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
 
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
diff --git a/toolkit/modules/Region.sys.mjs b/toolkit/modules/Region.sys.mjs
index 34a1f82fed4e..fce4933f0be8 100644
--- a/toolkit/modules/Region.sys.mjs
+++ b/toolkit/modules/Region.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const { AppConstants } = ChromeUtils.import(
diff --git a/toolkit/mozapps/extensions/internal/GMPProvider.sys.mjs b/toolkit/mozapps/extensions/internal/GMPProvider.sys.mjs
index ed87f38f60f2..b0aa2f6a040f 100644
--- a/toolkit/mozapps/extensions/internal/GMPProvider.sys.mjs
+++ b/toolkit/mozapps/extensions/internal/GMPProvider.sys.mjs
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const { AppConstants } = ChromeUtils.import(
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js
index 2e0bfdebd011..5f05c8a0fa7f 100644
--- a/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js
@@ -68,6 +68,14 @@ module.exports = {
         "mozilla/reject-lazy-imports-into-globals": "error",
       },
     },
+    {
+      files: ["**/*.mjs"],
+      rules: {
+        // This rule defaults to not allowing "use strict" in module files since
+        // they are always loaded in strict mode.
+        strict: "error",
+      },
+    },
     {
       files: ["**/*.jsm", "**/*.jsm.js"],
       rules: {