Most likely the CAA getting ready in case the negotiations fail. They did the same in 2016 when Monarch’s ATOL renewal was pushed to the line. It was slightly worrying to land in Palma de Mallorca to be greeted by a United B747 in case the ATOL license wasn’t renewed.
fortunately in 2016 all the aircraft flew back without having been put into action, at a great cost to the CAA. Lets hope that the same happens again this time round!