I'm struggling to understand why the closure of DSA is because of Brexit. Was the airport really that dependent on unemployed people in Romania coming to Lincolnshire to pick crops ? If so, that sounds like an airport with a very flimsy business plan. I don't think Brexit imposed particular difficulties on TUI as they seem to fly from many other UK airports.
I'm not trying to ridicule an argument... I'd just like to see a good and clear explanation of why Brexit was a substantial factor in DSA largely ceasing to be an airport