I have seen a tiny, not really obtrusive bug in the interplay between MiX file manager and the included MiX Player, on both Android 11 & Android 13. Both are custom ROMs and using Gesture Navigation. However, using the app switcher also causes the same effect, so I don't think its Gesture nav specific.
TO REPRODUCE:
If I use MiX to navigate to a folder containing MP3s, and click on one, then select "Player" to play the MP3, it all works as expected and the music starts. However, if I switch back to MiX, and then switch back to the Player, the music skips a beat or is momentarily interrupted or something that isn't good, when the player redraws itself on Top.
I first noticed it when using the navigation pill at the bottom of the screen to switch between the two last apps, but using the app switcher (also while on gesture nav) causes the same effect.