6S autonomous writing, and other weird stuff

My mother in law’s phone is supposedly doing a lot of weird things. The screen will zoom in and out on its own. Will spontaneously stop accepting her Lock screen passcode, then will eventually start accepting it again, and she can sometimes sit and watch it swipe type on its own. I’ve seen a screen recording of the swipe typing - she has no reason to try and put one over on me. Sometimes it’s in Safari, sometimes it’s in iMessage.

Several accessibility features were enabled and I thought she was inadvertently using them, so I disabled all but the font resizing. The issues persist.

The digitizer was just replaced. Still doing the odd behaviors.

ideas?