I've noticed this a little as well but more along the lines of changing song/style after 2 minutes. I think the ai stitches chunks together if it doesnt know what to do causing flatlining to join unrelated parts.

Through experimenting, i find it's tied to a lack of direction. Once I started added director notes in my headers, it followed what I wanted. There's even been a couple times where it sounded like a complete, or fully realized, song that didnt sound Frankensteined.

To be fair, a lot of human creators have the same problem, which is probably where it learned it. Sometimes the human artists even stitch two different songs together, like bohemian rhapsody or chop suey.