Filevault password out of sync autobiography
Apple platform security pdf
For the sake of discussion, I'll use AUserName to refer to the user whose password is out of sync.
Apple security features
The FileVault password is never going to update itself, it's always going to require user intervention.
Yubikey manager
It depends if it's a mobile or standard account but for mobile AD accounts I'd suggest turning off FileVault for that particular user only.
Apple security number
Open System Preferences > Privacy & Security > scroll down to "Filevault" > Click Enable Users > put in the Administrator password > Have the user put in their password > .