Ultimately what kills any effort to curb this behaviour is the fact that the perpetrator can always open another account.
If I was a maintainer of an open-source project, I would have a two-tier system:
-PRs from previous contributors.
-All others, sorted by lines of code, ascending.
Reasoning:
-Large PRs from someone without a track record are rare.
-It's not a huge ask to have people first solve a smaller problem.
-Small PRs are easy to verify - it's especially easy to tell if a given one-liner is impactful or just spam. Should also be easier to summarise it in the title.
-Don't quote me on that but I think LLMs are still bad at clear, concise, meaningful changes.