Bad management of the situation (or, in your world a bit like Conservative running the country compared to Labour)
Brexit changed things and created more red tape compared to Europe, agreed, but management did not adapt despite plenty of warning.
The U.K. provided huge furlough grants for employees to be retained but instead the airlines made a broad sweep of redundancies, which was very short sighted.
The airlines then got greedy and took way too many bookings coming out of Covid when they had no capacity to deliver. They obviously had no strategy to take on sufficient staff in this new Brexit climate to meet the demand they had created, unless of course you feel that putting faith in this government to make it all ok is acceptable behaviour.
Did Brexit change the landscape, yes.
Did Covid create a whole new situation not foreseen , yes.
Had Covid not happened would we have been in this situation of redundancies, no.
Would good management and lack of greed overcome these hurdles, yes.
So who is to blame? Brexit, Covid, Government, Management?