Since updating to this beta the fingerprint sensor is always lit on the always on display how can we turn off to stop screen burn in
It shouldn't cause burn in because it very slightly moves around.
If you want to turn it off go to the fingerprint settings in security and you can disable the icon in there
It is exactly as @ARamsay said (Thank you for sharing your knowledge! ).
So you should not be scared of the burn-in, but of course you can disable that option in Settings.