I don’t see this as a bug. Just use a white texture in the albedo slot. Then the base color and it’s alpha (using alpha blend) work correctly, controlling color and transparency. Nothing to fix here.
I do see it as a bug since it isn’t an issue in 20. In addition to that less texture is always better than more. Even if it’s just a 128x128 white one. We shouldn’t go back a step compared to where we were in 2020 and use workarounds as a bug fix.
Again, that’s not the point. There are multiple workarounds for a lot of issues but this is not how it should be! Bugs should be fixed and not worked around full stop