Final Fantasy IX has a bug on Switch that isn't huge, but it can certainly become annoying to audiophiles. While playing through the game, you might start to notice that music tracks will restart following each and every battle. This isn't supposed to happens, as tracks are meant to pick up where they left off after a battle. The really bad news is that this bug has very little chance of happening.
The same music bug was present in the PS4 version of the game, as well as the PC and mobile versions. If Square-Enix didn't fix the bug on those platforms, then it's likely the bug will remain on Switch as well.