Update StackNavigationManager.cs

src/Core/src/Platform/Windows/StackNavigationManager.cs

@@ -56,6 +56,12 @@ namespace Microsoft.Maui.Platform
 			FirePendingNavigationFinished();
 			_navigationFrame = null;
 			NavigationView = null;
+
+			if (_previousContent is not null)
+			{
+				_previousContent.Content = null;
+				_previousContent = null;
+			}
 		}
 
 		public virtual void NavigateTo(NavigationRequest args)