Webview on transparent WPF regions does not hittest.

Description
When WPF window has Allow Transparency and no style (completely transparent window).
And WebView2 is on window region where no other controls are visible (i.e. Panel hosting WebView2 are background transparent / opacity 0).
And WebView2 content is visible (though it may have opacity).
Clicks on WebView2 will pass through WebView2, not trigger webview2 content events, and activate desktop UI beneath the window.

Expectation would be that the WPF hit test takes into account WebView2's visible painted areas.
Ideal would also treat non-painted areas as pass-through.

Version
SDK: 1.0.790-prerelease
Runtime: Version 90.0.809.0
Framework: WPF, C#, XAML
OS: Windows 10 Pro Version 20H2 OS build 19042.804 Windows Feature Experience Pack 120.2212.551.0

Additional context
With the new DefaultBackgroundColor allowing transparency I have successfully rendered WebView2 content in a transparent window with alpha blending/composition on the desktop. The bug above however means that there can be no interaction with the content as the entire control is not hittested even for the areas of the control which are visible.

Re-enabling window background, or having other wpf controls visible behind or in-front of the webview2 will suddenly make the webview2 receive hittest in the regions where the other controls overlap.

AB#31911566

No source files or tests are identified in the report. Start by reproducing the transparent WPF window scenario described with WebView2, then compare hit testing with and without a visible WPF background or overlapping control; done means visible WebView2 content receives clicks while transparent areas retain the intended pass-through behavior.