How do I remove "Elliptical Magnifier" in Numbers on iPhone?

Quitting Numbers (swiping and quitting the app, not just moving it to the background) appears to be the popular way to get rid of it. Another is to restart your device (actually restarting it, not just locking it). I included the parenthetical additional instructions because not everyone knows there is a difference.

I don't recall if anyone discovered how it is getting turned on. You can find additional info if you do an internet search for "green oval numbers app" or "green circle numbers app" or "green ring numbers app".