In context it seems they're concerned about clear ownership of the code. It's lumped in with rules about not submitting code that might not have clear licensing or ownership. Here's the specific part from NetBSD's Commit Guidelines:

Code generated by a large language model or similar technology, such as GitHub/Microsoft's Copilot, OpenAI's ChatGPT, or Facebook/Meta's Code Llama, is presumed to be tainted code, and must not be committed without prior written approval by core.