That only means that FR24 / jetphotos.net databases have been updated to link to that registration rather than the test reg. The plane only emits the hex code, unless the pilots enter the registration as the call sign or flight number, as a lot of biz jets do. That's also why it does not now show a photo of the aircraft as they have not updated that part of their database to link the real reg to a photo !
Quite strange, MSN16 was also visible with final reg some days before TAC date and official delivery (day before delivery flight). So if it is similar, delivery would be today and flight tommorow? But I wonder the reason, maybe some legal stuff with the leasing company??