Current behavior

Create simple app, exactly as learn.microsoft.depth-shadow proposes it:

<ScrollViewer>
    <Grid Background="White">
        <Grid.Resources>
            <ThemeShadow x:Name="SharedShadow" />
        </Grid.Resources>

        <Grid x:Name="BackgroundGrid" Background="{ThemeResource ApplicationPageBackgroundThemeBrush}" />

        <Rectangle x:Name="Rectangle1" Height="100" Width="100" Fill="Turquoise" Shadow="{StaticResource SharedShadow}" />

        <Rectangle x:Name="Rectangle2" Height="100" Width="100" Fill="Turquoise" Shadow="{StaticResource SharedShadow}" />
    </Grid>
</ScrollViewer>

private void MainPage_Loaded(object sender, RoutedEventArgs e)
{
    /// Add BackgroundGrid as a shadow receiver and elevate the casting buttons above it
    SharedShadow.Receivers.Add(BackgroundGrid);

    Rectangle1.Translation += new Vector3(0, 0, 16);
    Rectangle2.Translation += new Vector3(120, 0, 132);
}

On WindowsAppSDK it shows two rectangles as expected:

On Desktop it shows two rectangles that overlap:

Then, resize the main window to trigger content refresh: two rectangles are shown as expected:

Expected behavior

No response

How to reproduce it (as minimally and precisely as possible)

MINIMAL REPRO PROJECT: UnoShadowApp.zip

Workaround

No response

Works on UWP/WinUI

Yes

Environment

No response

NuGet package version(s)

"Uno.Sdk": "5.5.49"

Affected platforms

No response

IDE

Visual Studio 2022

IDE version

No response

Relevant plugins

No response

Anything else we need to know?

No response