Book Depsitory is based in the UK. I have inadvertently ordered from them, to the Netherlands, as they had a “Bookdepository NL” store, which made it seem like they are an EU entity.
However, when the book arrived, I was hit by unexpected customs charges that were half the price of the book. Looking at recent reviews, there was a surge of these complaints from all customers in the Netherlands [1]
Perhaps the timing on these customs surges are accidental, of course. But I can’t imagine that Brexit helped with their EU sales.
[1] https://twitter.com/gergelyorosz/status/1638824647390003206