As someone on the other side of the PR, the current situation makes things awkward for me, too. Occasionally, I'll make an actual fix to scratch some particular itch I have with the software, and I'm hesitant to even open a PR, because it's just going to 1. pile yet another PR onto the maintainer, and 2. might get dismissed out of hand because it's mistaken for AI slop or other low-effort spam that these attackers are doing. So, I usually just fork, make the change in my own repo, and leave it at that.
Disabling PRs or limiting PRs to "contributors" would be a signal to me that I should just keep doing that and not contribute back to the main repo.
Yeah, I kinda stopped involving myself in other people's OSS projects a while ago for that reason. If I have an itch to scratch, I just use my fork. It usually feels like my itch isn't theirs and I always feel like I'm imposing on the maintainer's vision or at best just taking time away from them. I think maintainers have a lot of pressure to accept things because "open source!".
Totally get this. One thing we'd love to do is help make contribution patterns (not just guidelines) more visible to contributors, to help you get a better read of what's expected. Would that help? If so, where would you expect it to sit in your existing contribution flow?