Or if LLM output is copyrighted or sourced from copyrighted code - they can't take that risk, lest they face another "Google LLC v. Oracle America, Inc.". I think that lawsuit caused huge waves in the open source communities.

To be clear, that case did not decide copyrightability of APIs, just fair use in Google's specific circumstances. I wish the court had ruled that APIs themselves could not be copyrightable (after all, they are declarations of something, not the implementation) but it did what it loves to do and kicked the can down the road