For now, Mozilla's official stance is to oppose this proposal: https://github.com/mozilla/standards-positions/issues/852#issuecomment-1648820747

I wish that this kind of thing would generate enough outrage to increase Firefox' market share considerably (from the <3% it is today), and in that way deter websites from adopting it since they would block a larger share of users. Unfortunately, I think that might be too naive of me...