I think that's just an artifact, as they can also produce heavy metal scream singing etc. It just mimics something that was in the training data. My guess is t

I think that's just an artifact, as they can also produce heavy metal scream singing etc. It just mimics something that was in the training data. My guess is that they train the vocals and the music separately, the training data is trivial to create from any tracks with tools like with https://vocalremover.org/ https://vocalremover.org/.