Fix [Android] Title of FlyOutPage is not updating anymore after showing a NonFlyOutPage

src/Controls/src/Core/NavigationPage/NavigationPage.cs

@@ -585,7 +585,7 @@ void OnWindowChanged(object sender, EventArgs e)
 					}
 
 					var flyoutPage = _toolbar.FindParentOfType<FlyoutPage>();
-					if (flyoutPage != null && flyoutPage.Parent is IWindow && flyoutPage.Toolbar == _toolbar)
+					if (flyoutPage is not null && flyoutPage.Toolbar == _toolbar)
 					{
 						flyoutPage.Toolbar = null;
 					}

src/Controls/tests/TestCases.HostApp/Issues/Issue33615.cs

@@ -0,0 +1,81 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 33615, "[Android] Title of FlyOutPage is not updating anymore after showing a NonFlyOutPage", PlatformAffected.Android)]
+public class Issue33615 : TestFlyoutPage
+{
+	NavigationPage _navigationPage;
+
+	protected override void Init()
+	{
+		Flyout = new ContentPage
+		{
+			Title = "Menu",
+			Content = new Label { Text = "Flyout Menu" }
+		};
+
+		var detailPage1 = new ContentPage { Title = "DetailPage1" };
+		_navigationPage = new NavigationPage(detailPage1);
+		Detail = _navigationPage;
+
+		detailPage1.Content = new VerticalStackLayout
+		{
+			VerticalOptions = LayoutOptions.Center,
+			Children =
+			{
+				new Button
+				{
+					Text = "Show NonFlyoutPage",
+					AutomationId = "ShowNonFlyoutButton",
+					Command = new Command(() =>
+					{
+						this.Window.Page = new Issue33615NonFlyoutPage(this);
+					})
+				},
+				new Button
+				{
+					Text = "Navigate to DetailPage2",
+					AutomationId = "NavigateToDetailPage2Button",
+					Command = new Command(async () =>
+					{
+						await _navigationPage.PushAsync(new ContentPage
+						{
+							Title = "DetailPage2",
+							Content = new Label
+							{
+								Text = "DetailPage2",
+								AutomationId = "DetailPage2Label"
+							}
+						});
+					})
+				},
+				new Label
+				{
+					Text = "DetailPage1",
+					AutomationId = "DetailPage1Label"
+				}
+			}
+		};
+	}
+}
+
+class Issue33615NonFlyoutPage : ContentPage
+{
+	public Issue33615NonFlyoutPage(Page flyoutPage)
+	{
+		Title = "NonFlyoutPage";
+		Content = new VerticalStackLayout
+		{
+			VerticalOptions = LayoutOptions.Center,
+			Children =
+			{
+				new Label { Text = "NonFlyoutPage" },
+				new Button
+				{
+					Text = "Back to FlyoutPage",
+					AutomationId = "BackToFlyoutButton",
+					Command = new Command(() => this.Window.Page = flyoutPage)
+				}
+			}
+		};
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue33615.cs

@@ -0,0 +1,42 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue33615 : _IssuesUITest
+{
+	public Issue33615(TestDevice device) : base(device) { }
+
+	public override string Issue => "[Android] Title of FlyOutPage is not updating anymore after showing a NonFlyOutPage";
+
+	[Test]
+	[Category(UITestCategories.FlyoutPage)]
+	public void TitleUpdatesAfterShowingNonFlyoutPage()
+	{
+		// Wait for the FlyoutPage detail (DetailPage1) to load
+		App.WaitForElement("ShowNonFlyoutButton");
+
+		// Show a NonFlyoutPage by changing Window.Page
+		App.Tap("ShowNonFlyoutButton");
+
+		// Wait for the NonFlyoutPage to appear
+		App.WaitForElement("BackToFlyoutButton");
+
+		// Go back to the FlyoutPage
+		App.Tap("BackToFlyoutButton");
+
+		// Wait for the FlyoutPage to be restored with DetailPage1
+		App.WaitForElement("NavigateToDetailPage2Button");
+
+		// Navigate to DetailPage2 — the toolbar title should update to "DetailPage2"
+		App.Tap("NavigateToDetailPage2Button");
+
+		// Verify DetailPage2 is the current page
+		App.WaitForElement("DetailPage2Label");
+
+		// The toolbar title must match "DetailPage2" — use VerifyScreenshot to
+		// detect if the toolbar is frozen on the old title "DetailPage1"
+		VerifyScreenshot();
+	}
+}