Ungoogled-Chromium: libicui18n.so.69 is missing

  1. Read a thread when stepping in, would you have done so, you could grasp that the real issue is a non standard Webrtc problem between Firefox & BigBlueButton.
  2. admonishing is not polite.

@emninger : the Firefox trouble could also be due to the plugins you use.
Can you list them ?

grep -oP '},"name":"\K[^"]+' ~/.mozilla/firefox/*.*default*/addons.json

This test could also help:

https://test.webrtc.org/

[Edit] You can also check Pipewire is ok on your system as sound issues can happen if not, see second post on this thread: