Dirty from 10.3.1 or 10.2.x I don't remember.
If you rooted your phone and it is not needed for you, unroot it, flash rom again with clear cache and dalvik cache only then remove data of Google play services using twrp
It should works
Are you using any root (magisk, supersu)? Did you remove data of Google play services via twrp or only using Android ? You should remove that data via twrp.
Hmm for me it works. I've added my face and locked screen. After power button pressed I can see that phone recognized my face but I have to move up the screen
On MI8 without or with Magisk Google Pay doesn't work with this solution...
Edit: works but cannot be used beta Google Play Services, so first must remove beta update