Brexit plus big increase in Sojourn tax seem to had an effect. Plus of course, many Brit boats are owned by retirees of which a proportion will pack in sailing each year, sell the boat
and buy an RV or just pack it in.
My anecdotal evidence is that Brit expats often develop a real or anticipated health
concern and eventually seek to return to the comfort of the UK NHS.
Now that Croatia
is in the EU, Brits are now happier to sell a boat in Croatia rather than return to UK or other EU countries