My iPhone XS has stopped accepting Face ID

My iPhone Xr has stopped accepting Face ID. I recently updated to IOS 14.5.1, but the problem occurred promptly after updating process.

I have repeatedly restarted the phone; each time it tells me "Unable to activate Face ID on this iPhone." When I go to Settings > Face ID & Passcode > Set up Face ID, it tells me "Face ID is Not Available: Try setting up Face ID later."

How do I restore Face ID, which I need for my Due Mobile security software and numerous other programs?