Comment by asveikau
Sometimes when I log into a random website and I see a forced password reset, I wonder if it has been compromised, rather than setting a time-based expiry.
If a site owner knows that certain accounts are part of a database breach or something, a reasonable step would be to force the users to change the password at next login.
Another common reason to do a force password reset is if they've moved authentication providers and were not able to bring their hashes along. Some providers don't allow for hash export (Cognito, Entra).