There are a couple sound-quality based tells that I've noticed, off the top of my head

1. Usually weird little "flickers" of sound - like how a candle gives you mostly constant light but there are little flashes of bright and dark. AI generated music tends to have little distortions scattered throughout like that. As the models have improved they're less obvious but still absolutely there if you try to listen to any individual 'instrument' or 'track'

2. very low dynamic range - loud sounds and quiet sounds are much more similar volume than you'd expect from most real music, and things that are supposed to fade or taper-off in volume are unnatural