My device: Galaxy S20 5G (SM-G981U1), android version 11. Equalizer version is "build-908-arm64-play"
My issue is only with Pandora music, all other apps seem to work OK. What happens is: when a song starts, about 50% of the time the song plays at low volume (about half volume). It will continue to play at low volume until either the song ends, or I pause and start the music again. When i do the pause-play trick, the sound always returns to the correct volume. Every time the song changes, it's another 50/50 chance if the song is playing at the correct volume.
I don't have a headphone jack (rip), but I have tested this with my Bluetooth earbuds, and my portable headphone amp in both Bluetooth and USB DAC mode, all showed the same behavior. I also tried playing with all the options for Pandora in the 'known players' menu, but nothing seemed to fix the problem.