I think there are two different things at play here. All short haul at Gatwick except Domestic is part of EuroFlyer, so for example the staff operating it work for EF and so on. And has been the case since the reopening post-Covid.

However they are still transitioning the aircraft registrations over to the new AOC, so for example the G-MID A320s operating at LGW are not registered to EF. On these flights you won’t see them as ‘Operated by BA EuroFlyer’ in MMB and that won’t be announced on board.

This isn’t route specific. On my IBZ this week, it was a non-EF A320 aircraft on the the way out, and an EF A321 on the return.