Why is my face Id disabled?

Hello,

Apple has several documents dealing with Face ID issues depending upon if it is "disabled" or just "not working", both of which you use to describe your case..

This document explains what to do if you see a 'disabled' Face ID alert --> If an alert says Face ID has been disabled on your iPhone or iPad Pro - Apple Support

If you just have issues with Face ID not working properly, explore the list of things to try in this document: If Face ID isn't working on your iPhone or iPad Pro - Apple Support

If the first 8 don't solve the issue then use #9, contact Apple.