@abj

Tried 2 different HDMI cables and same cable works perfectly with the main 4.8 version I’ve got on a 2nd SD card. These issues seem to be with the bullseye beta images but don’t think it’s a RetroPie problem as Batocera had the exact same issues on their newest versions for the Pi3B.

Check from RetroPie-Setup -> Audio -> Mixer that the Hdmi volume is not zero or mute. You can try also the last option in the Audio tab, Reset to default, an restart ES.

@illando unfortunately I don't know
I really don't see the card speed being much of an issue because the raspberry pi doesn't have a very fast read write speed to start with as far as I know

But if you have one laying around or easily accessible guess it wouldn't hurt to try that