So here's the thing: I've been releasing my code as open source for nearly 15 years. When I write something for me, I release it for other people. Inevitably, I eventually stop needing that thing, so I stop spending time on it.
When a PR comes in for a project I haven't actively worked on in a while, handling that PR requires me to reacquaint myself with the old code, remember how and why I made certain choices, consider whether accepting the PR would create any new maintenance burdens for me or would potentially introduce problems for users who've been using a stable and unchanged program for years now. If I decide it's worthwhile, then I have to test it. Maybe my old project has tests; maybe it doesn't. If it doesn't, that means I have to get it running and test manually.
More often than not, a PR will contain questionable code or inconsistent formatting or something else that requires some back and forth with the author. This takes time out of my day (often out of several days due to the async nature of