New law change to stop touts buying up driving test slots and then Ticketmastering the prices . This was done by allowing "driving instructors" to book them but obviously scum scamps found out that this could be abused, this law change from May 12th makes it illegal to book for someone else (other sections exist within it for other permutations of reasonable adjustments etc).
This is the reason and the action taken from what I can see anyway.
New driving rules for UK drivers to start on May 12
u/GreyScope — 19 days ago