I've had a weirdo-acting iPhone on a couple of occasions over the past 13(!) years. A full factory reset/rebuild (just treated it like a new phone) fixed it both times. I didn't do a "restore from backup", in case the problem was some sort of corruption/glitch in the existing system, so I just wiped everything clean and built completely fresh, and those issues all went away. This happened on my iPhone 4 and briefly-owned, "stopgap" iPhone 5c, both well over five years ago (the 2010-2012 and late-2015 timeframes).
It's a hassle, and not my favorite way to spend time, but I'd exhausted all other fixes/options. And it wasn't that bad, especially when they acted right again. Time well spent; that's why God makes rainy Saturdays.
"Well, I can't do much else today...".