At a guess, Oceania, Port of Charleston, and some other cruise line (remember: "berthing conflict") have been negotiating for some time. If so, O likely figured "we're not going to do this in '24" long before they gave up on an overnight in '23.
...and unless we get another "itinerary change" email with word that the first stop in "Nassau" is changed to "GSC", we'll keep expecting to dock in Nassau on Day 2 😞