

Not sure how straightforward this is, but maybe instead of fixing things directly, point out to them what the fix needs to be. “Oh, you have an extra comma here. Try removing that and then see if it works.”
By forcing them to be the ones that work in their code base, and also forcing them to have to fix their own problems (even if you hand-hold them through it), then maybe they’ll start to show a little more care.
At some point you have to let them fail. Remind them of it again, so that when they cause a major issue in prod you can point out that you communicated it to them multiple times. If this team keeps causing outages (and aren’t covered for by other teams) then, hopefully, management high enough will become aware of it and start to crackdown on them. I know you said elsewhere you don’t want them to lose their jobs but if they can’t do it, they shouldn’t have it. It’s not like you’re sabotaging them - you’re still helping them with advice and warnings. If despite that help they still can’t get by, then them getting terminated is the remaining best outcome.