We are seeing megacorporations (SlopenAI, Antslopic, Microslop, etc.) distributing derivatives of open-source code (their LLMs) without attribution.

Can you point to some specific examples of products shipped by the companies I assume you're referring to here that are in fact unattributed derivative works of GPL-licensed software?

Or are you saying that you think anything generated by an LLM qualifies as a derivative work of anything included in its training data?