Was tearing my hair out this morning when I couldn’t listen to podcasts on the way to work. I updated my S23 Ultra to ONE UI 7 yesterday evening and this morning Android Auto was working fine EXCEPT that I had no audio. Adjustment of volume in the car and on my phone were unsuccessful.

The solution was to make a quick phone call and now audio works fine again. I have no idea why it worked or why audio wasn’t working to begin with - but I thought I would share in case it helps anyone else.