24-hr cancel, Is this a FFC or ETC?
The date issue is easy as all new ETC/FFC are still 31 Dec 2023. So old or new, 31 Dec 2023
If ETC, you are likely to get a "new" one, a new PIN, but other than that nothing different -- however, it can take days for this to happen
If FFC, it will go to the same PNR and trends to happen faster.
These are handled by the refunds department and an phone agent can not issue,
It is best to avoid travel credits if strong possibility of using the 24 hour cancellation