G–VIIA as an example. It's due to operate BA67 PHL today, 5th and BA143 DEL tomorrow, 6th. If you search both them flights it's already showing G–VIIA.

Today's BA550 FCO has had 6 aircraft changes within 24h and yet flightradar24 is showing the correct current reg.

The info must be getting from BA to the website, not sure how tho!