Sound stops working overnight

For the last few days (less than a week), I noticed my alarm wasn't going off in the morning.

When I checked a little more, it wasn't just my alarm - none of my sounds would work. Videos, music, alarms, sounds/haptics - nothing.

I restarted the phone and that fixed the problem - temporarily until the next overnight period.

Last night I verified all sounds were working properly prior to going to bed - watched a video, played a song, tested the alarm. This morning - same problem - no sound :(

I have and iPhone12 with the latest iOS update (15.4.1)

Any thoughts/ideas? Anyone else having this issue? I saw another thread from 2019 with the same problem, but no fix.