It’s just a name change to stop the very few that getting their knickers in a twist about this sort of stuff (ie. the muttering minority that normally have unofficial RAF Twitter accounts). It is being implemented on 1st July 2022. Basically:
Air Recruit replaces Leading Aircraftman (AC)
Air Specialist (2nd Class) replaces Leading Aircraftman (LAC)
Air Specialist (1st Class) replaces Senior Aircraftman (SAC)
Air Specialist Technician (1st Class) replaces Senior Aircraftman (Technician) (SAC(T))
Not a big deal really. Same pay scales and same insignia. However, I do think they ballsed up the last one. Personally I would have gone for Air Technician and given them a 4 bladed prop badge again - as there is only one Technician rank at that level then there is no need for the 1st Class anyway.
Of course we also have Airborne Specialists now (the common name for the ‘flying Fighter Controllers’, Airborne Technicians, Mission Intelligence Coordinators, non-Aircrew Flight Test Engineers and Cabin Crew) as a term for Ground Branch/Trade/Profession personnel employed on airborne duties or operating an aircraft. So there is room for a bit of confusion - but no more than the aviator thing that goes against the definition in every English dictionary in the world. So 2 steps forward and 2 steps back in my opinion.