Video image moving autonomously for iPad user.

[BTTO]

I have a Zoom license. On a recent Zoom video session with 6 attendees one participant was using an iPad and her image began to unexpectedly move further away and then back closer all by itself.  This has happened with her image in several previous video sessions.  How can that autonomous image movement action be stopped from happening?  I don't know how or why this is happening.