I was chatting with one of my composition students about Kendrick Lamar (and Drake), and I introduced the student to this piece by Bernd Alois Zimmermann. I think it’s pretty proto-diss, esp. last movement (and the Wikipedia has a whole article on “Diss”): https://youtu.be/9GO43MIA8gM?si=HL929oAfPKkibC1C