@shadoom I don't use amiberry so I can't say. You can try installing sdl2 2.0.20, install the wip audiosettings from cmitu's repo (it adds the option for hdmi audio) and then install amiberry again. Retropie's default is 2.0.10. I believe .20 was causing problems with some games but I mainly use libretro cores so it doesn't affect me.
Checking retropie's sdl branch, you can experiment with versions .16 and .18 though I don't know which version fixed the issues with bullseye.