Face ID apps
I have the problem for some apps Face ID prompt does not appear for example PayPal Amazon banking app and it worked before . Does not even ask for passcode or Face ID.
on website works and settings are fine
iPhone 12
Did you not get a prompt as shown in the pic below when you logged into the App?
See the pic below here where you can find out which apps have access to Face-ID. If you do see this on your iPhone then you will have go into the settings of the App (Not iPhone Settings). Ypu may also delete the app and re-install it.