Just discovered my (dozens of) Smart Mailboxes have vanished from Apple Mail after 13.2.1 Ventura update. Just finished with Apple Support: They “may have been deleted” and we can’t help you. More discussion at Apple Communities here.
Citizens: If you use Apple Mail and are now with Ventura 13.2.1 you may want to confirm your Smart Mailboxes are present and actually working. That is all.