It's exactly as you said. They probably validate after the ceremony to ensure only those that show up get marked as citizens. so that's probably why they ask for the 3 days. It takes time for the database to update and if someone rushes to get a passport, the certificate may come back as invalid or something.Yes, we basically knew that about the in-person and certificates. Was more mentioning because of the specific instructions at ceremony that need to wait before applying for passport.
Whereas the digital certificate is sent after the ceremony so the validation is down beforehand.
