ca350 Do you mean the HEX CODE again? Not final registration.
I did mean final registration, although it's not reflective on the callsign. I think we both know this pretty well , as part of the delivery process, the transponder gets re-boxed to the hex code that corresponds to the final registration. So online with hex code = online with final registration, even though the final registration may or may not get reflected in the callsign.
There are cases where the hex code was not inputted into FR24 database to be mapped to the reg, that's when we saw an empty aircraft profile on the FR24 page or whatever flight tracker. But this is not related to what Airbus and the airline are doing.