I would have questions about how they work with a team and structure.
Are they going to be okay with planning work out two weeks ahead? Sometimes hobbyists do like 80% of a task and then wander off (it’s me with some of my hobbies).
Are they going to be okay following existing code standards? I don’t want to deal with someone coming in and trying to relitigate line lengths or other formatting stuff, or someone who’s going to reject the idea of standards altogether.
Are they going to be okay giving and getting feedback from peers? Sometimes code review can be hard for people. I recently had a whole snafu at work where someone was trying to extend some existing code into something it wasn’t meant to do*, and he got really upset when the PR was rejected.
Do they write tests? Good ones? I feel like a lot of self taught hobbyists don’t. A lot of professionals don’t. I don’t want to deal with someone’s 4000 line endpoint that has no tests but “just works see I manually tested it”
The other day I was updating something and a test failed. I looked at it and saw I had written it, and left a comment that said like “{Coworker} says this test case is important”. Welp. He was right. Was a subtle wrong that could’ve gone out to customers, but the wrong stayed just on my local thanks to that test.