Noisy audio in Firefox 68.10.0esr (64-bit) on Debian Buster

Yesterday I started my laptop (cold boot), upgraded Firefox to 68.10.0esr (64-bit) (Debian Buster firefox-esr package at version 68.10.0esr-1~deb10u1) and then joined a conference. Someone complained that my audio was noisy. So I disconnected and rejoined with Chromium and they reported my sound was good. There were only a few users (maybe 5 or 6) in the conference at the time.

If I manage to duplicate the problem, what other information should I report?