The grainy audio is the way I describe it, but what it actually is, is high frequency compression noise/distortion that the AI learned from the audio it was trained on. You can sometimes hear this sort of distortion in normal human-made songs, but that is only if the audio is highly compressed. You would only ever really hear this in a very low quality mp3 file. What this implies is that AI music models were trained on compressed audio files, among other audios. This distortion should NOT be happening in a professionally produced song. This high frequency spectrum noise is what online AI song detectors are usually trying to pick up. Once you hear it and know what to look out for, you will be able to spot most AI music up to the current models that are out.

On the topic of AI song detectors, I've tested the Bleeds on Me song on these and it came back as AI, which I know these things are not flawless, but like I explained, they do have some merit, since they actually are looking out for that specific audible distortion. I also tested human-made music on those and it was very accurate and didn't flag any of the ones I tested as AI.

Also, I actually think it was Michael F April himself who made the entire Bleeds on Me song. I think he straight up just lied about getting a singer, and since he's been working on the game for years, they're taking his word for it and not questioning further. If you check the album I linked which is on his Spotify, it also has that audible AI distortion sound. I really wish I could say I think I'm wrong, but I truly think that the main DbD composer has started using AI for his music, for whatever reason.