Sound Bug After Big Sur Update?

Greetings Nathan-J,

We understand that you are having some difficulty with your Mac speakers, and we'd like to help. Begin by following the guidance found here:

If the internal speakers on your Mac aren't working

If any issues remain after completing those steps, Contact Apple Support for further assistance.

Take care.

I also have this issue on my 2017 iMac after updating to Big Sur, sometimes after automatic login it happens, I can press the volume up and down keys and there is no audio feedback (which I usually have on). That is how I know it happens at login. Sometimes it works just fine. When I logout and log back in the audio returns. This is not hardware but software obviously, and the only change would be the system update. Maybe with all the security features the system isn't letting itself use audio privileges in certain instances? As an avid programmer I am leaning towards it being a little bug here.