[Android] Fix Switch thumb shadow missing when ThumbColor is set

src/Controls/tests/TestCases.HostApp/Issues/Issue19676.cs

@@ -0,0 +1,45 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 19676, "Android Switch Control Thumb Shadow missing when ThumbColor matches background", PlatformAffected.Android)]
+public class Issue19676 : ContentPage
+{
+	public Issue19676()
+	{
+		BackgroundColor = Color.FromArgb("#F2F5F8");
+
+		Content = new VerticalStackLayout
+		{
+			Padding = 20,
+			Spacing = 20,
+			Children =
+			{
+				new Label
+				{
+					Text = "Switch with ThumbColor matching background",
+					FontSize = 16,
+					FontAttributes = FontAttributes.Bold,
+				},
+				new Label
+				{
+					Text = "The switch thumb should be visible with a shadow, even though ThumbColor matches the background.",
+					FontSize = 14,
+				},
+				new Switch
+				{
+					IsToggled = true,
+					ThumbColor = Color.FromArgb("#F2F5F8"),
+					OnColor = Colors.Red,
+					AutomationId = "TestSwitch",
+					Margin = new Thickness(10, 20, 15, 0),
+					VerticalOptions = LayoutOptions.Center
+				},
+				new Label
+				{
+					Text = "Expected: Switch thumb is visible with shadow",
+					FontSize = 14,
+					TextColor = Colors.Gray,
+				}
+			}
+		};
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue19676.cs

@@ -0,0 +1,20 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue19676 : _IssuesUITest
+{
+	public override string Issue => "Android Switch Control Thumb Shadow missing when ThumbColor matches background";
+
+	public Issue19676(TestDevice device) : base(device) { }
+
+	[Test]
+	[Category(UITestCategories.Switch)]
+	public void SwitchThumbShouldBeVisibleWithShadow()
+	{
+		App.WaitForElement("TestSwitch");
+		VerifyScreenshot();
+	}
+}

src/Core/src/Platform/Android/SwitchExtensions.cs

@@ -28,7 +28,13 @@ public static void UpdateThumbColor(this ASwitch aSwitch, ISwitch view)
 
 			if (thumbColor is not null)
 			{
-				aSwitch.ThumbDrawable?.SetColorFilter(thumbColor, FilterMode.SrcAtop);
+				// Use ThumbTintList instead of SetColorFilter to preserve the thumb shadow
+				// SetColorFilter flattens the drawable and removes the shadow effect
+				aSwitch.ThumbTintList = ColorStateListExtensions.CreateDefault(thumbColor.ToPlatform());
+			}
+			else
+			{
+				aSwitch.ThumbTintList = null;
 			}
 		}