Some CSS styles can't be set using ExecuteScriptAsync?

Description
I can't seem to set any of the scrollbar CSS properties using ExecuteScriptAsync. This call works and sets the text colour to red:
await webview.ExecuteScriptAsync("document.body.style.color='#f00';");

But this call does nothing and no CSS styles are added to the body tag:
await webview.ExecuteScriptAsync("document.body.style.scrollbarFaceColor='#f00';");

These used to work with the old webview. My goal here is that our application has a light and a dark theme and if the user selects the dark theme we want to make the scrollbars dark in the WebView2 control as well.

Version
SDK: 1.0.1210.39
Runtime: Public channel v101.0.1210.53 (Official build) (64-bit)
Framework: .NET 6 Desktop
OS: Windows 11

Repro Steps
In the NavigationCompleted event handler just try using the 2 code examples above. The first one works and the second one does nothing.

Thanks for your help, keep up the great work!

AB#40023481

Start with the NavigationCompleted handler and the two ExecuteScriptAsync calls shown in the issue. Reproduce the working text-color change and the scrollbar-property change against the stated SDK and runtime versions, then determine whether the behavior is an API or CSS support limitation. Done means the supported behavior and any required workaround are documented or the defect is fixed and verified.