By taking out the back row of seating on its A319 fleet, EasyJet said it will be able to fly with three cabin crew instead of four. That would limit numbers on board to a maximum 150 passengers. EasyJet said it was an effective way of operating the fleet while "building additional resilience and flexibility" into the airline's operations. Flights would still meet Civil Aviation Authority (CAA) regulations on the required number of cabin crew, which is based on the number of physical seats, rather than passengers on board.
https://www.bbc.co.uk/news/business-61370175