[Shell] Update logic for iOS large title display in ShellItemRenderer

src/Controls/src/Core/Compatibility/Handlers/Shell/iOS/ShellItemRenderer.cs

@@ -455,11 +455,19 @@ void UpdateLargeTitles()
 			if (page is null || !OperatingSystem.IsIOSVersionAtLeast(11))
 				return;
 
+			// Shell doesn't have the property PrefersLargeTitles, so we should not update the large titles
+			// if users doen't explicitly set the LargeTitleDisplay property on the Page.
+			// todo net 11: Add PrefersLargeTitles to Shell and use that here.
+			if (!page.IsSet(PlatformConfiguration.iOSSpecific.Page.LargeTitleDisplayProperty))
+			{
+				return;
+			}
+
 			var largeTitleDisplayMode = page.OnThisPlatform().LargeTitleDisplay();
 
 			if (SelectedViewController is UINavigationController navigationController)
 			{
-				navigationController.NavigationBar.PrefersLargeTitles = largeTitleDisplayMode == LargeTitleDisplayMode.Always;
+				navigationController.NavigationBar.PrefersLargeTitles = largeTitleDisplayMode != LargeTitleDisplayMode.Never;
 				var top = navigationController.TopViewController;
 				if (top is not null)
 				{

src/Controls/tests/TestCases.HostApp/Issues/Issue33037.cs

@@ -0,0 +1,51 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 33037, "iOS Large Title display disappears when scrolling in Shell", PlatformAffected.iOS)]
+public class Issue33037 : TestShell
+{
+	protected override void Init()
+	{
+		var page = new ContentPage
+		{
+			Title = "Large Title Test"
+		};
+
+		// Explicitly set LargeTitleDisplay to Always — this should show a large title
+		Microsoft.Maui.Controls.PlatformConfiguration.iOSSpecific.Page.SetLargeTitleDisplay(
+			page,
+			Microsoft.Maui.Controls.PlatformConfiguration.iOSSpecific.LargeTitleDisplayMode.Always);
+
+		var scrollView = new ScrollView
+		{
+			AutomationId = "TestScrollView",
+			Content = new VerticalStackLayout
+			{
+				Children =
+				{
+					new Label
+					{
+						Text = "Large Title Test Page",
+						AutomationId = "PageTitle",
+						FontSize = 18,
+						Margin = new Thickness(20, 10)
+					}
+				}
+			}
+		};
+
+		// Add enough items to make the page scrollable
+		var layout = (VerticalStackLayout)scrollView.Content;
+		for (int i = 0; i < 30; i++)
+		{
+			layout.Children.Add(new Label
+			{
+				Text = $"Item {i}",
+				AutomationId = $"Item{i}",
+				Margin = new Thickness(20, 5)
+			});
+		}
+
+		page.Content = scrollView;
+		AddContentPage(page);
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue33037.cs

@@ -0,0 +1,34 @@
+#if TEST_FAILS_ON_ANDROID && TEST_FAILS_ON_WINDOWS
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue33037 : _IssuesUITest
+{
+	public Issue33037(TestDevice testDevice) : base(testDevice)
+	{
+	}
+
+	public override string Issue => "iOS Large Title display disappears when scrolling in Shell";
+
+	[Test]
+	[Category(UITestCategories.Shell)]
+	public void LargeTitleTransitionsOnScroll()
+	{
+		// Verify page loaded with large title visible
+		App.WaitForElement("PageTitle");
+
+		// Take a screenshot before scrolling to verify large title is shown
+		VerifyScreenshot("Issue33037_BeforeScroll");
+
+		// Scroll down to trigger the large title → standard title transition
+		App.ScrollDown("TestScrollView");
+		App.ScrollDown("TestScrollView");
+
+		// Take screenshot after scrolling — title should have transitioned to standard size
+		VerifyScreenshot("Issue33037_AfterScroll", retryTimeout: TimeSpan.FromSeconds(2));
+	}
+}
+#endif