As other have mentioned, and I'm the same. Leaving "Co-Authored by:" feels like open disclosure of how the project was created.

That way if a consumer does not want to use LLM generated/assisted software, it's easy for them to do that without having to search around in the codebase for "AI Tells".

Removing those would feel like I was mis-representing my coding abilities (LLMs are better at most coding than I am) :)