Well, after installing KB5001391, I had one more crash shortly. However, only after this did the "News and interests" feature, also part of this update, show up. So it is conceivable that the patch of our real interest had not been live first. Since that 2nd reboot, my system has been up and running, i.e. for 5.5 days so far.
To put this in context, my previous incidents happened at such intervals:
4/14, 4/18, 5/2, 5/7, 5/9, 5/9
Should my system crash again, I'll (try to remember to) notify you guys...