Filevault login issue after upgrade

[jameson]

Every now and then both after normal patch updates or now major OS upgrade from Cataline to Big Sur I experience users that are unable to login at the filevault.
If it was only one user I would say it maybe the wrong password, but during the years I have often experienced difference users suddenly unable to login to after upgrade

Are other seeing that issue also sometimes ? - Just wondering what it is that I cannot see why an upgrade of any kind just can go in a "flush" filevault login password.

[junjishimazaki]

It appears that the user's secure token password is out of sync with the local password. When it comes to the FileVault password, it all depends on where users change their password when it comes time to update their password. When a user has to update their password where do you direct them to change it? How often do the users reboot their Mac? Are the macs bound to the domain?

[bootrec]

I have a few users that are getting locked out of their computers at the FV2 screen and I'm oblivious as to what is causing this. Only recourse is to have them log in with a "support" account I manually add to all my computers (because we're not allowed to provide the password for the mgmt account we deploy). Would really like to pin down what is causing this.