Freezes in nbclassic with ipykernel 7.1 #1471

A few of us have recently noticed that nbclassic has been freezing randomly when doing "run all cells". It's not something we can reliably reproduce, but it happens to me for instance a few times per day. Restarting the kernel and re-running normally fixes it -- sometimes I have to do it twice.

I can't figure out what's the cause, and aren't sure how to debug. No errors appear in the terminal or devtools console.

Any thoughts about possible causes, or ways I could try to debug this?