Fluent2 Light LayerFillColorAlt Is Unusable

[robert-abeo]

Describe the bug

In Dark theme LayerFillColorAlt is set to #0DFFFFFF -- mostly transparent white.
In Light theme LayerFillColorAlt is set to #FFFFFF -- full white.

Obviously, full white in light theme doesn't make a lot of sense -- you can't see it. This should be mostly transparent black IMO (a very light grey). That gives it the contrast necessary to see it and also is symmetrical with what is done in dark theme.

Steps to reproduce the bug

See Fluent2 Dark/Light Resources, the problem is visible just looking at the colors in code.

Expected behavior

LayerFillColorAlt should be visible on the ApplicationBackgroundColor (and others) in light theme. It is not visible in a lot of cases since it is pure white.... in a light theme which is also mostly white.

Screenshots

TBD

NuGet package version

None

Windows version

No response

Additional context

Transferred from WPF: dotnet/wpf#10481

This issue itself seems to be a very old mistake by the design team. They choose a bad color for contrast here. This isn't a bug related to code.