https://www.thisismoney.co.uk/money/...nes-trade.html
I think it's quite clear from the quotes in that article from Green that Brexit played a part in the airline's demise - bemoaning they weren't given the level playing field they were promised.
Whether it was the straw that broke the camel's back, or combined with COVID etc, poor management, they all contributed to a lethal cocktail that tipped it finally over the edge.