Computer spontaneously restarts

System info: Lenovo ThinkPad T14s Gen 3, Ubuntu 22.04.3 LTS

Problem: The computer spontaneously restarts I think about an hour or so after re-awaking from a suspend-on-lid-shut event: I will be in the middle of using the laptop and it will suddenly turn itself off and then restart with no input from me. Other events involving shutting the lid seem to result in this as well, like hibernating by shutting the lid. In contrast, if I select hibernate from the menu and then shut the lid after the laptop turns off then everything seems to be OK. So it seems to be something to do with shutting the lid when the laptop is on. The long delay between re-awaking the laptop and the spontaneous restarting makes this problem hard to investigate for me so I would appreciate some pointers!