[Bullseye] Firefox fails on ARMv6

[MichaIng]

The latest Bullseye Firefox ESR package version 91.4.1esr-1~deb11u1+rpi1 fails with an "illegal instruction" error on all ARMv6 RPi models. It looks like the same underlying issue which makes Chromium (from the RPi repository) fail on those models the same way: https://github.com/RPi-Distro/chromium-browser/issues/21

I'm not sure whether something can be done (reasonably) as the RPi Foundation/devs decided to not work on ARMv6 support for Chromium either, but probably an older functional version (like the one shipped with Buster) could be additionally made available as a workaround, though for end users it is not trivial to install/downgrade to an older version and prevent automatic upgrades via hold or pinning.

Best regards and happy new year,

Micha