iphone – How to disable a floating right arrow button that makes FaceTime calls

My mom keeps accidentally FaceTiming me and we think it’s because of a floating gray button with a left angle bracket on it:

floating right arrow button

I’ve been trying to help her remotely turn it off. She must have accidentally activated it somehow today, but she is unaware of how it happened.

Assistive touch is turned off. Nothing in control center is highlighted. I’ve tried searching for it on my phone to figure out what enables it, but I cannot figure it out. I have googled and all I find is suggestions to turn off assistive tough, but that is off. I don’t even know how to google it. I’ve been trolling through assistive access, FaceTime, and phone settings and can find nothing related to that button.

What is this button and how do you disable it?