The print job didn’t fail, so I’m going to write this off as a kernel bug until/unless it happens again. I’m just glad I can run long jobs again!

Checked that and the systemd timers. No dice. However, this problem started right around the time I updated my kernel package, and there was another update that I applied yesterday. I connected the printer and let it sit overnight. No midnight disconnections.

I’m running a print job now that should run past midnight. Fingers crossed that this was just some kind of transient kernel bug!