Pressing it results in a message popping up saying “Interior scan deactivated” which to be honest doesn’t help much.Looks like motion sensor for security
Yes. There is an entry for driver's door buttons and it covers the obvious things like the window controls but there's no mention of this one.Did you check the owner's manual?
Or a child that won’t sit still for a few hours while you’re enjoying yourself in the pub.Turns off interior alarm sensors, for example if you were to leave your dog in the car... As suggested above...