This is something I noticed with the "Independent Voices" colorway collection; we use the toolbar color at 70% opacity, and that's not new behavior, it goes back to Proton, but it's problematic and especially obvious with themes that have a toolbar background that's not very light or dark (e.g. "Balanced" colorways), and are as such more prone to producing subpar contrast with the text color.

Here's how "Visionary — Balanced" would look with the opacity reduction removed. This would be my proposed solution here.

I have no insight as to why the opacity was reduced in the first place (although I reviewed that patch). Things like these weren't really explained when Proton was developed. It's not like the find bar is permanently visible, and when the user has explicitly opened it, I don't understand why we'd want to tune it down rather than drawing attention to it.

Set release status flags based on info from the regressing bug 1703043

https://hg.mozilla.org/mozilla-central/rev/5aabf1d7d378

Managed to reproduce the issue on Nightly from 2022-08-09.
Verified the fix using latest Nightly 106.0a1 and Nightly 105.0a1 (after the fix) on macOS 12.3, Ubuntu 18.04 x64 and Windows 10 x 64 and I can't seem to reproduce the issue anymore.