Has anything changed for durable unsubscribes?

Wondering whether anything changed recently in the durable unsubscribe process. I am working with an instance where several entities are migrating to Marketo and every time a migration happens we import the unsubscribed records that were collected in the legacy platforms into Marketo.

As Marketo should also remember that unsubscribe status after the record was deleted based on the master unsubscribe list, we remove the newly created records from that unsubscribe list the next day, so the contacts database does not contain records we'll never do anything with. It used to be that when one of those email addresses enters Marketo again at a later stage, they would immediately be flagged as unsubscribed again based on the master record that was retained in the background.

I am now testing this process and I don't see the immediate update to unsubscribed status happening. However, for some records I do see a durable unsubscribe activity being logged hours later.

Has anyone seen this behaviour before? I would hate to have to keep these records in the database moving forward to make sure the unsubscribe status is remembered...