Even though the README links to live tests (browser JS libs), the person submitting the PR rarely includes tests so that's one issue. Sure I can say "I'll be happy to accept this if you could please add some tests?" but then that leads to the 2nd issue. PRs are rarely quality PRs and if I want to add the feature I end up having to re-write whatever they were trying to add from scratch.
I know people are claiming LLMs will make things worse for many projects but an LLM can likely at least read what's there and try to make things that follow the conventions?
I also know I'm under no obligation to accept any PRs. It's not that easy to say no for me, depending on the ask.