Dear Debian Maintainer,

There appears to be a severe sound issue affecting
some users that may ultimately trace back to the tlp package.
Please see the thread at

https://bbs.archlinux.org/viewtopic.php?id=243004

and in particular comment #7 by Toolfox.

I vaguely remember fixing a problem with buster that
turned out to be related to tlp. And then recently
I upgraded to bullseye and faced the same problem.
I had no sound at all. Nothing. But "fixed" the issue merely by
uninstalling the tlp package. Upon reboot, sound was
back so tlp is definitely preventing sound for some users.

This is a beguiling bug to track down because there's few
clues to follow and nobody suspects a power management package
to ultimately be the cause of such a severe sound bug.
The bug may be related to whether users are on battery or wall power
as comment #7 explains. I almost always use wall power so it affected
me.