Fixed the OnPlatform does not work for header property in Collection view

src/Controls/src/Core/Xaml/TypeConversionExtensions.cs

@@ -224,6 +224,17 @@ internal static object ConvertTo(this object value, Type toType, Func<TypeConver
 				}
 			}
 
+			// When toType is object and value is OnPlatform<T>, we need to return the wrapped value from IWrappedView
+			if (toType is object && value is IWrappedValue { Value: var wrappedValue })
+			{
+				if (wrappedValue is null)
+				{
+					return value;
+				}
+
+				return wrappedValue;
+			}
+
 			var platformValueConverterService = DependencyService.Get<INativeValueConverterService>();
 
 			object platformValue = null;

src/Controls/tests/TestCases.HostApp/Issues/Issue25124.xaml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Issues.Issue25124"
+             Title="Issue25124">
+    <Grid>
+        <CollectionView AutomationId="CollectionView">
+            <CollectionView.ItemsSource>
+                <x:Array Type="{x:Type x:String}">
+                    <x:String>A</x:String>
+                    <x:String>B</x:String>
+                </x:Array>
+            </CollectionView.ItemsSource>
+            <CollectionView.Header>
+                <OnPlatform x:TypeArguments="View">
+                    <On Platform="Android">
+                        <Label Text="Android Header"/>
+                    </On>
+                    <On Platform="WinUI">
+                        <Label Text="WinUI Header"/>
+                    </On>
+                    <On Platform="iOS">
+                        <Label Text="IOS Header"/>
+                    </On>
+                    <On Platform="MacCatalyst">
+                        <Label Text="Mac Header"/>
+                    </On>
+                </OnPlatform>
+            </CollectionView.Header>
+        </CollectionView>
+    </Grid>
+</ContentPage>

src/Controls/tests/TestCases.HostApp/Issues/Issue25124.xaml.cs

@@ -0,0 +1,10 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 25124, "OnPlatform does not work in the Header and Footer of CollectionView", PlatformAffected.UWP | PlatformAffected.Android | PlatformAffected.iOS | PlatformAffected.macOS)]
+public partial class Issue25124 : ContentPage
+{
+	public Issue25124()
+	{
+		InitializeComponent();
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue25124.cs

@@ -0,0 +1,22 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue25124 : _IssuesUITest
+{
+	public Issue25124(TestDevice testDevice) : base(testDevice)
+	{
+	}
+
+	public override string Issue => "OnPlatform does not work in the Header and Footer of CollectionView";
+
+	[Test]
+	[Category(UITestCategories.CollectionView)]
+	public void ShouldDisplayHeaderBasedOnOnPlatform()
+	{
+		App.WaitForElement("CollectionView");
+		VerifyScreenshot();
+	}
+}