Just a heads up: yesterday, I decided to upgrade all of my packages. I know: what a silly thing to do when having the computer working is critical for work. Anyway...
My system is mostly Debian testing (with a couple of bits from sid). In upgrading, I lost sound completely. I spent a few hours trying to sort this out, playing with pulseaudio, alsamixer, ... Eventually, I rebooted with the older kernel (version 5.6.0-1-amd64) which sorted (some) things out. I have sound again although only through my HDMI display, not through the headphones, but that's enough for now. -- Eric S Fraga via Emacs 28.0.50 & org 9.3.7 on Debian bullseye/sid