[WinUI] Adding Toolbar item to ContentPage has unusual drop shadow on menu.

[michaelrinderle]

Description

Adding a toolbar item in WinUI has an unusual drop shadow on a new vanilla project.

Adding

<ContentPage.ToolbarItems>
    <ToolbarItem Text="test" Order="Secondary" Priority="0" />
</ContentPage.ToolbarItems>    

to MainPage.Xaml results in the following.

Steps to Reproduce

1. Create new MAUI App.
2. Add toolbar item to MainPage.Xaml

Link to public reproduction project repository

No response

Version with bug

8.0.3

Is this a regression from previous behavior?

Yes, this used to work in Xamarin.Forms

Last version that worked well

8.0.3

Affected platforms

Windows

Affected platform versions

No response

Did you find any workaround?

No

Relevant log output

No response

[Auto72]

Related to #18258

[XamlTest]

Verified this on Visual Studio Enterprise 17.9.0 Preview 2(8.0.3). Repro on Windows 11, not repro on Android 14.0-API34, iOS 16.4 and MacCatalyst with below Project: 19166.zip