diff --git a/airflow/providers/amazon/aws/hooks/base_aws.py b/airflow/providers/amazon/aws/hooks/base_aws.py
index ab011f3038..56e49b3a56 100644
--- a/airflow/providers/amazon/aws/hooks/base_aws.py
+++ b/airflow/providers/amazon/aws/hooks/base_aws.py
@@ -29,6 +29,7 @@ import logging
 from typing import Any, Dict, Optional, Tuple, Union
 
 import boto3
+from botocore.credentials import ReadOnlyCredentials
 from botocore.config import Config
 from cached_property import cached_property
 
@@ -393,7 +394,7 @@ class AwsBaseHook(BaseHook):
         session, _ = self._get_credentials(region_name)
         return session
 
-    def get_credentials(self, region_name: Optional[str] = None) -> Tuple[Optional[str], Optional[str]]:
+    def get_credentials(self, region_name: Optional[str] = None) -> ReadOnlyCredentials:
         """
         Get the underlying `botocore.Credentials` object.
 
diff --git a/airflow/providers/amazon/aws/transfers/dynamodb_to_s3.py b/airflow/providers/amazon/aws/transfers/dynamodb_to_s3.py
index 10cadd58d5..0d95ee7861 100644
--- a/airflow/providers/amazon/aws/transfers/dynamodb_to_s3.py
+++ b/airflow/providers/amazon/aws/transfers/dynamodb_to_s3.py
@@ -25,7 +25,7 @@ import json
 from copy import copy
 from os.path import getsize
 from tempfile import NamedTemporaryFile
-from typing import Any, Callable, Dict, Optional
+from typing import Any, Callable, Dict, Optional, IO
 from uuid import uuid4
 
 from airflow.models import BaseOperator
@@ -34,11 +34,11 @@ from airflow.providers.amazon.aws.hooks.s3 import S3Hook
 from airflow.utils.decorators import apply_defaults
 
 
-def _convert_item_to_json_bytes(item):
+def _convert_item_to_json_bytes(item: Dict[str, Any]) -> bytes:
     return (json.dumps(item) + '\n').encode('utf-8')
 
 
-def _upload_file_to_s3(file_obj, bucket_name, s3_key_prefix):
+def _upload_file_to_s3(file_obj: IO, bucket_name: str, s3_key_prefix: str) -> None:
     s3_client = S3Hook().get_conn()
     file_obj.seek(0)
     s3_client.upload_file(
@@ -102,7 +102,7 @@ class DynamoDBToS3Operator(BaseOperator):
         s3_key_prefix: str = '',
         process_func: Callable[[Dict[str, Any]], bytes] = _convert_item_to_json_bytes,
         **kwargs,
-    ):
+    ) -> None:
         super().__init__(**kwargs)
         self.file_size = file_size
         self.process_func = process_func
@@ -111,7 +111,7 @@ class DynamoDBToS3Operator(BaseOperator):
         self.s3_bucket_name = s3_bucket_name
         self.s3_key_prefix = s3_key_prefix
 
-    def execute(self, context):
+    def execute(self, context) -> None:
         table = AwsDynamoDBHook().get_conn().Table(self.dynamodb_table_name)
         scan_kwargs = copy(self.dynamodb_scan_kwargs) if self.dynamodb_scan_kwargs else {}
         err = None
@@ -126,7 +126,7 @@ class DynamoDBToS3Operator(BaseOperator):
                 _upload_file_to_s3(f, self.s3_bucket_name, self.s3_key_prefix)
             f.close()
 
-    def _scan_dynamodb_and_upload_to_s3(self, temp_file, scan_kwargs, table):
+    def _scan_dynamodb_and_upload_to_s3(self, temp_file: IO, scan_kwargs: dict, table: Any) -> IO:
         while True:
             response = table.scan(**scan_kwargs)
             items = response['Items']
diff --git a/airflow/providers/amazon/aws/transfers/gcs_to_s3.py b/airflow/providers/amazon/aws/transfers/gcs_to_s3.py
index 695087e861..d474f310c2 100644
--- a/airflow/providers/amazon/aws/transfers/gcs_to_s3.py
+++ b/airflow/providers/amazon/aws/transfers/gcs_to_s3.py
@@ -19,7 +19,7 @@
 This module contains Google Cloud Storage to S3 operator.
 """
 import warnings
-from typing import Iterable, Optional, Sequence, Union, Dict
+from typing import Iterable, Optional, Sequence, Union, Dict, List, cast
 
 from airflow.models import BaseOperator
 from airflow.providers.amazon.aws.hooks.s3 import S3Hook
@@ -100,21 +100,21 @@ class GCSToS3Operator(BaseOperator):
     def __init__(
         self,
         *,  # pylint: disable=too-many-arguments
-        bucket,
-        prefix=None,
-        delimiter=None,
-        gcp_conn_id='google_cloud_default',
-        google_cloud_storage_conn_id=None,
-        delegate_to=None,
-        dest_aws_conn_id=None,
-        dest_s3_key=None,
-        dest_verify=None,
-        replace=False,
+        bucket: str,
+        prefix: Optional[str] = None,
+        delimiter: Optional[str] = None,
+        gcp_conn_id: str = 'google_cloud_default',
+        google_cloud_storage_conn_id: Optional[str] = None,
+        delegate_to: Optional[str] = None,
+        dest_aws_conn_id: str = 'aws_default',
+        dest_s3_key: str,
+        dest_verify: Optional[Union[str, bool]] = None,
+        replace: bool = False,
         google_impersonation_chain: Optional[Union[str, Sequence[str]]] = None,
         dest_s3_extra_args: Optional[Dict] = None,
         s3_acl_policy: Optional[str] = None,
         **kwargs,
-    ):
+    ) -> None:
         super().__init__(**kwargs)
 
         if google_cloud_storage_conn_id:
@@ -139,7 +139,7 @@ class GCSToS3Operator(BaseOperator):
         self.dest_s3_extra_args = dest_s3_extra_args or {}
         self.s3_acl_policy = s3_acl_policy
 
-    def execute(self, context):
+    def execute(self, context) -> List[str]:
         # list all files in an Google Cloud Storage bucket
         hook = GCSHook(
             google_cloud_storage_conn_id=self.gcp_conn_id,
@@ -183,7 +183,7 @@ class GCSToS3Operator(BaseOperator):
                 self.log.info("Saving file to %s", dest_key)
 
                 s3_hook.load_bytes(
-                    file_bytes, key=dest_key, replace=self.replace, acl_policy=self.s3_acl_policy
+                    cast(bytes, file_bytes), key=dest_key, replace=self.replace, acl_policy=self.s3_acl_policy
                 )
 
             self.log.info("All done, uploaded %d files to S3", len(files))
diff --git a/airflow/providers/amazon/aws/transfers/glacier_to_gcs.py b/airflow/providers/amazon/aws/transfers/glacier_to_gcs.py
index fb43d0fb10..3506003181 100644
--- a/airflow/providers/amazon/aws/transfers/glacier_to_gcs.py
+++ b/airflow/providers/amazon/aws/transfers/glacier_to_gcs.py
@@ -72,17 +72,17 @@ class GlacierToGCSOperator(BaseOperator):
     def __init__(
         self,
         *,
-        aws_conn_id="aws_default",
-        gcp_conn_id="google_cloud_default",
+        aws_conn_id: str = "aws_default",
+        gcp_conn_id: str = "google_cloud_default",
         vault_name: str,
         bucket_name: str,
         object_name: str,
         gzip: bool,
-        chunk_size=1024,
-        delegate_to=None,
+        chunk_size: int = 1024,
+        delegate_to: Optional[str] = None,
         google_impersonation_chain: Optional[Union[str, Sequence[str]]] = None,
         **kwargs,
-    ):
+    ) -> None:
         super().__init__(**kwargs)
         self.aws_conn_id = aws_conn_id
         self.gcp_conn_id = gcp_conn_id
@@ -94,7 +94,7 @@ class GlacierToGCSOperator(BaseOperator):
         self.delegate_to = delegate_to
         self.impersonation_chain = google_impersonation_chain
 
-    def execute(self, context):
+    def execute(self, context) -> str:
         glacier_hook = GlacierHook(aws_conn_id=self.aws_conn_id)
         gcs_hook = GCSHook(
             gcp_conn_id=self.gcp_conn_id,
diff --git a/airflow/providers/amazon/aws/transfers/google_api_to_s3.py b/airflow/providers/amazon/aws/transfers/google_api_to_s3.py
index ca17bed221..a8ee7db14d 100644
--- a/airflow/providers/amazon/aws/transfers/google_api_to_s3.py
+++ b/airflow/providers/amazon/aws/transfers/google_api_to_s3.py
@@ -23,8 +23,8 @@ import json
 import sys
 from typing import Optional, Sequence, Union
 
-from airflow.models import BaseOperator
-from airflow.models.xcom import MAX_XCOM_SIZE
+from airflow.models import BaseOperator, TaskInstance
+from airflow.models.xcom import MAX_XCOM_SIZE, XCOM_RETURN_KEY
 from airflow.providers.amazon.aws.hooks.s3 import S3Hook
 from airflow.providers.google.common.hooks.discovery_api import GoogleDiscoveryApiHook
 from airflow.utils.decorators import apply_defaults
@@ -98,20 +98,20 @@ class GoogleApiToS3Operator(BaseOperator):
     def __init__(
         self,
         *,
-        google_api_service_name,
-        google_api_service_version,
-        google_api_endpoint_path,
-        google_api_endpoint_params,
-        s3_destination_key,
-        google_api_response_via_xcom=None,
-        google_api_endpoint_params_via_xcom=None,
-        google_api_endpoint_params_via_xcom_task_ids=None,
-        google_api_pagination=False,
-        google_api_num_retries=0,
-        s3_overwrite=False,
-        gcp_conn_id='google_cloud_default',
-        delegate_to=None,
-        aws_conn_id='aws_default',
+        google_api_service_name: str,
+        google_api_service_version: str,
+        google_api_endpoint_path: str,
+        google_api_endpoint_params: dict,
+        s3_destination_key: str,
+        google_api_response_via_xcom: Optional[str] = None,
+        google_api_endpoint_params_via_xcom: Optional[str] = None,
+        google_api_endpoint_params_via_xcom_task_ids: Optional[str] = None,
+        google_api_pagination: bool = False,
+        google_api_num_retries: int = 0,
+        s3_overwrite: bool = False,
+        gcp_conn_id: str = 'google_cloud_default',
+        delegate_to: Optional[str] = None,
+        aws_conn_id: str = 'aws_default',
         google_impersonation_chain: Optional[Union[str, Sequence[str]]] = None,
         **kwargs,
     ):
@@ -132,7 +132,7 @@ class GoogleApiToS3Operator(BaseOperator):
         self.aws_conn_id = aws_conn_id
         self.google_impersonation_chain = google_impersonation_chain
 
-    def execute(self, context):
+    def execute(self, context) -> None:
         """
         Transfers Google APIs json data to S3.
 
@@ -151,7 +151,7 @@ class GoogleApiToS3Operator(BaseOperator):
         if self.google_api_response_via_xcom:
             self._expose_google_api_response_via_xcom(context['task_instance'], data)
 
-    def _retrieve_data_from_google_api(self):
+    def _retrieve_data_from_google_api(self) -> dict:
         google_discovery_api_hook = GoogleDiscoveryApiHook(
             gcp_conn_id=self.gcp_conn_id,
             delegate_to=self.delegate_to,
@@ -167,21 +167,21 @@ class GoogleApiToS3Operator(BaseOperator):
         )
         return google_api_response
 
-    def _load_data_to_s3(self, data):
+    def _load_data_to_s3(self, data: dict) -> None:
         s3_hook = S3Hook(aws_conn_id=self.aws_conn_id)
         s3_hook.load_string(
             string_data=json.dumps(data), key=self.s3_destination_key, replace=self.s3_overwrite
         )
 
-    def _update_google_api_endpoint_params_via_xcom(self, task_instance):
+    def _update_google_api_endpoint_params_via_xcom(self, task_instance: TaskInstance) -> None:
         google_api_endpoint_params = task_instance.xcom_pull(
             task_ids=self.google_api_endpoint_params_via_xcom_task_ids,
             key=self.google_api_endpoint_params_via_xcom,
         )
         self.google_api_endpoint_params.update(google_api_endpoint_params)
 
-    def _expose_google_api_response_via_xcom(self, task_instance, data):
+    def _expose_google_api_response_via_xcom(self, task_instance: TaskInstance, data: dict) -> None:
         if sys.getsizeof(data) < MAX_XCOM_SIZE:
-            task_instance.xcom_push(key=self.google_api_response_via_xcom, value=data)
+            task_instance.xcom_push(key=self.google_api_response_via_xcom or XCOM_RETURN_KEY, value=data)
         else:
             raise RuntimeError('The size of the downloaded data is too large to push to XCom!')
diff --git a/airflow/providers/amazon/aws/transfers/hive_to_dynamodb.py b/airflow/providers/amazon/aws/transfers/hive_to_dynamodb.py
index 574d73a0d3..9a89719815 100644
--- a/airflow/providers/amazon/aws/transfers/hive_to_dynamodb.py
+++ b/airflow/providers/amazon/aws/transfers/hive_to_dynamodb.py
@@ -21,6 +21,7 @@ This module contains operator to move data from Hive to DynamoDB.
 """
 
 import json
+from typing import Optional, Callable
 
 from airflow.models import BaseOperator
 from airflow.providers.amazon.aws.hooks.dynamodb import AwsDynamoDBHook
@@ -64,18 +65,18 @@ class HiveToDynamoDBOperator(BaseOperator):
     def __init__(  # pylint: disable=too-many-arguments
         self,
         *,
-        sql,
-        table_name,
-        table_keys,
-        pre_process=None,
-        pre_process_args=None,
-        pre_process_kwargs=None,
-        region_name=None,
-        schema='default',
-        hiveserver2_conn_id='hiveserver2_default',
-        aws_conn_id='aws_default',
+        sql: str,
+        table_name: str,
+        table_keys: list,
+        pre_process: Optional[Callable] = None,
+        pre_process_args: Optional[list] = None,
+        pre_process_kwargs: Optional[list] = None,
+        region_name: Optional[str] = None,
+        schema: str = 'default',
+        hiveserver2_conn_id: str = 'hiveserver2_default',
+        aws_conn_id: str = 'aws_default',
         **kwargs,
-    ):
+    ) -> None:
         super().__init__(**kwargs)
         self.sql = sql
         self.table_name = table_name
diff --git a/airflow/providers/amazon/aws/transfers/imap_attachment_to_s3.py b/airflow/providers/amazon/aws/transfers/imap_attachment_to_s3.py
index bf65b8f56d..b303d42aef 100644
--- a/airflow/providers/amazon/aws/transfers/imap_attachment_to_s3.py
+++ b/airflow/providers/amazon/aws/transfers/imap_attachment_to_s3.py
@@ -57,16 +57,16 @@ class ImapAttachmentToS3Operator(BaseOperator):
     def __init__(
         self,
         *,
-        imap_attachment_name,
-        s3_key,
-        imap_check_regex=False,
-        imap_mail_folder='INBOX',
-        imap_mail_filter='All',
-        s3_overwrite=False,
-        imap_conn_id='imap_default',
-        s3_conn_id='aws_default',
+        imap_attachment_name: str,
+        s3_key: str,
+        imap_check_regex: bool = False,
+        imap_mail_folder: str = 'INBOX',
+        imap_mail_filter: str = 'All',
+        s3_overwrite: bool = False,
+        imap_conn_id: str = 'imap_default',
+        s3_conn_id: str = 'aws_default',
         **kwargs,
-    ):
+    ) -> None:
         super().__init__(**kwargs)
         self.imap_attachment_name = imap_attachment_name
         self.s3_key = s3_key
@@ -77,7 +77,7 @@ class ImapAttachmentToS3Operator(BaseOperator):
         self.imap_conn_id = imap_conn_id
         self.s3_conn_id = s3_conn_id
 
-    def execute(self, context):
+    def execute(self, context) -> None:
         """
         This function executes the transfer from the email server (via imap) into s3.
 
diff --git a/airflow/providers/amazon/aws/transfers/mongo_to_s3.py b/airflow/providers/amazon/aws/transfers/mongo_to_s3.py
index b996e10ec7..58edc93ae2 100644
--- a/airflow/providers/amazon/aws/transfers/mongo_to_s3.py
+++ b/airflow/providers/amazon/aws/transfers/mongo_to_s3.py
@@ -16,6 +16,7 @@
 # specific language governing permissions and limitations
 # under the License.
 import json
+from typing import Optional, Any, Iterable, Union, cast
 
 from bson import json_util
 
@@ -44,16 +45,16 @@ class MongoToS3Operator(BaseOperator):
     def __init__(
         self,
         *,
-        mongo_conn_id,
-        s3_conn_id,
-        mongo_collection,
-        mongo_query,
-        s3_bucket,
-        s3_key,
-        mongo_db=None,
-        replace=False,
+        mongo_conn_id: str,
+        s3_conn_id: str,
+        mongo_collection: str,
+        mongo_query: Union[list, dict],
+        s3_bucket: str,
+        s3_key: str,
+        mongo_db: Optional[str] = None,
+        replace: bool = False,
         **kwargs,
-    ):
+    ) -> None:
         super().__init__(**kwargs)
         # Conn Ids
         self.mongo_conn_id = mongo_conn_id
@@ -70,7 +71,7 @@ class MongoToS3Operator(BaseOperator):
         self.s3_key = s3_key
         self.replace = replace
 
-    def execute(self, context):
+    def execute(self, context) -> bool:
         """
         Executed by task_instance at runtime
         """
@@ -80,13 +81,15 @@ class MongoToS3Operator(BaseOperator):
         if self.is_pipeline:
             results = MongoHook(self.mongo_conn_id).aggregate(
                 mongo_collection=self.mongo_collection,
-                aggregate_query=self.mongo_query,
+                aggregate_query=cast(list, self.mongo_query),
                 mongo_db=self.mongo_db,
             )
 
         else:
             results = MongoHook(self.mongo_conn_id).find(
-                mongo_collection=self.mongo_collection, query=self.mongo_query, mongo_db=self.mongo_db
+                mongo_collection=self.mongo_collection,
+                query=cast(dict, self.mongo_query),
+                mongo_db=self.mongo_db,
             )
 
         # Performs transform then stringifies the docs results into json format
@@ -100,7 +103,7 @@ class MongoToS3Operator(BaseOperator):
         return True
 
     @staticmethod
-    def _stringify(iterable, joinable='\n'):
+    def _stringify(iterable: Iterable, joinable: str = '\n') -> str:
         """
         Takes an iterable (pymongo Cursor or Array) containing dictionaries and
         returns a stringified version using python join
@@ -108,7 +111,7 @@ class MongoToS3Operator(BaseOperator):
         return joinable.join([json.dumps(doc, default=json_util.default) for doc in iterable])
 
     @staticmethod
-    def transform(docs):
+    def transform(docs: Any) -> Any:
         """
         Processes pyMongo cursor and returns an iterable with each element being
                 a JSON serializable dictionary
diff --git a/airflow/providers/amazon/aws/transfers/mysql_to_s3.py b/airflow/providers/amazon/aws/transfers/mysql_to_s3.py
index ce6ed54789..33ffd59e00 100644
--- a/airflow/providers/amazon/aws/transfers/mysql_to_s3.py
+++ b/airflow/providers/amazon/aws/transfers/mysql_to_s3.py
@@ -101,7 +101,7 @@ class MySQLToS3Operator(BaseOperator):
         if "header" not in self.pd_csv_kwargs:
             self.pd_csv_kwargs["header"] = header
 
-    def _fix_int_dtypes(self, df):
+    def _fix_int_dtypes(self, df: pd.DataFrame) -> None:
         """
         Mutate DataFrame to set dtypes for int columns containing NaN values."
         """
@@ -113,7 +113,7 @@ class MySQLToS3Operator(BaseOperator):
                     # set to dtype that retains integers and supports NaNs
                     df[col] = np.where(df[col].isnull(), None, df[col]).astype(pd.Int64Dtype)
 
-    def execute(self, context):
+    def execute(self, context) -> None:
         mysql_hook = MySqlHook(mysql_conn_id=self.mysql_conn_id)
         s3_conn = S3Hook(aws_conn_id=self.aws_conn_id, verify=self.verify)
         data_df = mysql_hook.get_pandas_df(self.query)
diff --git a/airflow/providers/amazon/aws/transfers/redshift_to_s3.py b/airflow/providers/amazon/aws/transfers/redshift_to_s3.py
index fe51401fd6..9bc97936a6 100644
--- a/airflow/providers/amazon/aws/transfers/redshift_to_s3.py
+++ b/airflow/providers/amazon/aws/transfers/redshift_to_s3.py
@@ -104,7 +104,7 @@ class RedshiftToS3Operator(BaseOperator):
                 'HEADER',
             ]
 
-    def execute(self, context):
+    def execute(self, context) -> None:
         postgres_hook = PostgresHook(postgres_conn_id=self.redshift_conn_id)
         s3_hook = S3Hook(aws_conn_id=self.aws_conn_id, verify=self.verify)
 
diff --git a/airflow/providers/amazon/aws/transfers/s3_to_redshift.py b/airflow/providers/amazon/aws/transfers/s3_to_redshift.py
index 5852c46dfb..9abbe0a8ef 100644
--- a/airflow/providers/amazon/aws/transfers/s3_to_redshift.py
+++ b/airflow/providers/amazon/aws/transfers/s3_to_redshift.py
@@ -87,13 +87,11 @@ class S3ToRedshiftOperator(BaseOperator):
         self.verify = verify
         self.copy_options = copy_options or []
         self.autocommit = autocommit
-        self._s3_hook = None
-        self._postgres_hook = None
 
-    def execute(self, context):
-        self._postgres_hook = PostgresHook(postgres_conn_id=self.redshift_conn_id)
-        self._s3_hook = S3Hook(aws_conn_id=self.aws_conn_id, verify=self.verify)
-        credentials = self._s3_hook.get_credentials()
+    def execute(self, context) -> None:
+        postgres_hook = PostgresHook(postgres_conn_id=self.redshift_conn_id)
+        s3_hook = S3Hook(aws_conn_id=self.aws_conn_id, verify=self.verify)
+        credentials = s3_hook.get_credentials()
         copy_options = '\n\t\t\t'.join(self.copy_options)
 
         copy_query = """
@@ -113,5 +111,5 @@ class S3ToRedshiftOperator(BaseOperator):
         )
 
         self.log.info('Executing COPY command...')
-        self._postgres_hook.run(copy_query, self.autocommit)
+        postgres_hook.run(copy_query, self.autocommit)
         self.log.info("COPY command complete...")
diff --git a/airflow/providers/amazon/aws/transfers/s3_to_sftp.py b/airflow/providers/amazon/aws/transfers/s3_to_sftp.py
index 97b1918d7d..c94ff5f6c5 100644
--- a/airflow/providers/amazon/aws/transfers/s3_to_sftp.py
+++ b/airflow/providers/amazon/aws/transfers/s3_to_sftp.py
@@ -50,8 +50,15 @@ class S3ToSFTPOperator(BaseOperator):
 
     @apply_defaults
     def __init__(
-        self, *, s3_bucket, s3_key, sftp_path, sftp_conn_id='ssh_default', s3_conn_id='aws_default', **kwargs
-    ):
+        self,
+        *,
+        s3_bucket: str,
+        s3_key: str,
+        sftp_path: str,
+        sftp_conn_id: str = 'ssh_default',
+        s3_conn_id: str = 'aws_default',
+        **kwargs,
+    ) -> None:
         super().__init__(**kwargs)
         self.sftp_conn_id = sftp_conn_id
         self.sftp_path = sftp_path
@@ -60,12 +67,12 @@ class S3ToSFTPOperator(BaseOperator):
         self.s3_conn_id = s3_conn_id
 
     @staticmethod
-    def get_s3_key(s3_key):
+    def get_s3_key(s3_key: str) -> str:
         """This parses the correct format for S3 keys regardless of how the S3 url is passed."""
         parsed_s3_key = urlparse(s3_key)
         return parsed_s3_key.path.lstrip('/')
 
-    def execute(self, context):
+    def execute(self, context) -> None:
         self.s3_key = self.get_s3_key(self.s3_key)
         ssh_hook = SSHHook(ssh_conn_id=self.sftp_conn_id)
         s3_hook = S3Hook(self.s3_conn_id)
diff --git a/airflow/providers/amazon/aws/transfers/sftp_to_s3.py b/airflow/providers/amazon/aws/transfers/sftp_to_s3.py
index 6cf1a734ba..482537f0b2 100644
--- a/airflow/providers/amazon/aws/transfers/sftp_to_s3.py
+++ b/airflow/providers/amazon/aws/transfers/sftp_to_s3.py
@@ -50,8 +50,15 @@ class SFTPToS3Operator(BaseOperator):
 
     @apply_defaults
     def __init__(
-        self, *, s3_bucket, s3_key, sftp_path, sftp_conn_id='ssh_default', s3_conn_id='aws_default', **kwargs
-    ):
+        self,
+        *,
+        s3_bucket: str,
+        s3_key: str,
+        sftp_path: str,
+        sftp_conn_id: str = 'ssh_default',
+        s3_conn_id: str = 'aws_default',
+        **kwargs,
+    ) -> None:
         super().__init__(**kwargs)
         self.sftp_conn_id = sftp_conn_id
         self.sftp_path = sftp_path
@@ -60,12 +67,12 @@ class SFTPToS3Operator(BaseOperator):
         self.s3_conn_id = s3_conn_id
 
     @staticmethod
-    def get_s3_key(s3_key):
+    def get_s3_key(s3_key: str) -> str:
         """This parses the correct format for S3 keys regardless of how the S3 url is passed."""
         parsed_s3_key = urlparse(s3_key)
         return parsed_s3_key.path.lstrip('/')
 
-    def execute(self, context):
+    def execute(self, context) -> None:
         self.s3_key = self.get_s3_key(self.s3_key)
         ssh_hook = SSHHook(ssh_conn_id=self.sftp_conn_id)
         s3_hook = S3Hook(self.s3_conn_id)
diff --git a/airflow/providers/google/cloud/hooks/gcs.py b/airflow/providers/google/cloud/hooks/gcs.py
index 1eb17ce88f..68ac78c13e 100644
--- a/airflow/providers/google/cloud/hooks/gcs.py
+++ b/airflow/providers/google/cloud/hooks/gcs.py
@@ -260,7 +260,9 @@ class GCSHook(GoogleBaseHook):
             destination_bucket.name,  # type: ignore[attr-defined]
         )
 
-    def download(self, object_name: str, bucket_name: Optional[str], filename: Optional[str] = None) -> str:
+    def download(
+        self, object_name: str, bucket_name: Optional[str], filename: Optional[str] = None
+    ) -> Union[str, bytes]:
         """
         Downloads a file from Google Cloud Storage.
 
diff --git a/airflow/providers/google/cloud/operators/bigquery.py b/airflow/providers/google/cloud/operators/bigquery.py
index 0686b33e2f..c208d2a2d8 100644
--- a/airflow/providers/google/cloud/operators/bigquery.py
+++ b/airflow/providers/google/cloud/operators/bigquery.py
@@ -947,9 +947,7 @@ class BigQueryCreateEmptyTableOperator(BaseOperator):
                 delegate_to=self.delegate_to,
                 impersonation_chain=self.impersonation_chain,
             )
-            schema_fields = json.loads(
-                gcs_hook.download(gcs_bucket, gcs_object).decode("utf-8")  # type: ignore[attr-defined]
-            )  # type: ignore[attr-defined]
+            schema_fields = json.loads(gcs_hook.download(gcs_bucket, gcs_object))
         else:
             schema_fields = self.schema_fields
 
@@ -1189,8 +1187,7 @@ class BigQueryCreateExternalTableOperator(BaseOperator):
                 delegate_to=self.delegate_to,
                 impersonation_chain=self.impersonation_chain,
             )
-            schema_object = gcs_hook.download(self.bucket, self.schema_object)
-            schema_fields = json.loads(schema_object.decode("utf-8"))  # type: ignore[attr-defined]
+            schema_fields = json.loads(gcs_hook.download(self.bucket, self.schema_object))
         else:
             schema_fields = self.schema_fields