As a maintainer of a Very Large open source project, I have not found this to be the case. I have not found that AI/LLM tools have generated noticably more noise. The occasional low-effort PR existed before ChatGPT and Copilot, and it continues to exist after it. 'Banning AI' does not absolve your responsibility to review PRs, nor do I believe does it make your job actually easier.
I believe I've noticed only one 'LLM spam' comment on an issue needlessly comparing different Javascript package mangers.
To be clear, I don't think this is true right now. But if the technology does improve just a bit further, it will be easy enough to be spammable and it will be abused.
I believe I've noticed only one 'LLM spam' comment on an issue needlessly comparing different Javascript package mangers.