Good evening, revbill222—Your reply prompted me to check the version of iOS, and sure enough I'd missed the update to 14.4.1. Well, that's done. Now I'd like to respond to your questions and add to the information I provided in my OP.
The behavior I described occurs at random, it seems, while my wife is using common iPhone apps: Messages, Mail, and Safari, for example. We both use apps that we know don't support landscape orientation—banking and medical care apps are two that come to mind. The teeth-grinding and cursing start when, say, Messages simply refuses to rotate. We've found that shutting down the misbehaving app and relaunching can help. When that fails, we shut down and restart the phone itself. Both those techniques can help, but don't you know it's a hassle when you're in a hurry.
As for reinstalling iOS—I have not done exactly what you suggested, but before my initial post I had reset her iPhone. I chose Settings—>General—>Reset—>Erase All Content and Settings. The article you linked to suggests that I should use those steps when I can't update or restore my iPhone. I had no trouble resetting the phone. Since resetting, the phone has behaved as it should.
This situation reminds me of when my car has displayed something that looks like trouble, but I can't make the problem appear once I've got a mechanic standing by. Everybody has had those experiences, and I suppose this could be something similar. Your thoughts?
