The background noise of the storm that accompanies some battles does not turn off after the battle is over. to get rid of it, you need to either restart the game or start a new battle with a different background sound.
and the latter does not always help.
This only happens with the sounds of a storm, I have not seen anything like this with other background sounds.
This happens on stages with ambient wind blowing in the background. From 0.36, the Desert and Snow/Tundra stages were the most likely to trigger this issue.
I would also like to add that similar I have noticed also with the sound of the echo in the caves, such as dungeon Clockwork halls. The background sound there sometimes rattles, crackles, and after the battle continues to overlap other sounds.