It reminds me of a PR I once saw (don't remember which project) in which a first-time contributor opened a PR rewriting the project's entire website in their favourite new framework. The maintainers calmly replied to the effect of, before putting in the work, it might have been best to quickly check if we even want this. The contributor liked the framework so much that I'm sure they believed it was an improvement. But it's the same tone-deafness I now see in many vibe coders who don't seem to understand that OSS projects involve other people and demand some level of consensus and respect.
But still the crux of the matter is: Massive changes require buy-in from other maintainers BEFORE the changes even start.
[1] https://github.com/aio-libs/aiosmtpd [2] https://github.com/aio-libs/aiosmtpd/pull/202
They did: the main point being made is "I'm not reading 13k LOCs when there's been no proposal and discussion that this is something we might want, and how we might want to have it implemented". Which is an absolutely fair point (there's no other possible answer really, unless you have days to waste) whether the code is AI-written or human-written.