FB19413975. Appears to be reproducing on Seed 9.

Does not appear to work on Beta 8 either.

Oh just using a color with a lower opacity works. .fill(Color(white: 1, opacity: 0.2)) Ideally materials or glass would nest in widgets like within an app.

I agree there should be a preset that allows for this. Creating controls that have the same appearance as the tab bar as a 3rd party is not possible currently. I would greatly appreciate this for my app.