Just became aware of the regional pricing difference and though I'd better check something before flipping out :)
So if I connect to GOG via a European exit server, GOG lists game X for €0.79. If I connect to GOG from a UK exit server, GOG lists the same game X for €1.19 (using the Euro currency view, which is available at the foot of the page). That's a mark-up of €0.40.
In the UK tax of 20% is included in price listings. If the European price is without tax, it would have to be taxed at just over 50% at checkout (which I can't see because my account is region-locked) to be the same price as the UK.
I don't/can't believe the EU tax rate for such a purchase is 50%, but like I say, before I flip out I thought I'd better ask for some community feedback first...
Nothing to do with taxes. Nor with this topic, which is for the currency exchange rate for equal value.
The regional price matrix is just whatever the publishers get away with and can vary from game to game. Just randomly checked Cyberpunk 2077: Phantom Liberty, Endless Space 2 Definitive Edition, Weird West: Definitive Edition, Heroes of Might and Magic 4 Complete and Master of Magic. GB price was higher than US price but lower than EU price for the first two (technically also for the last, but by 4 cents, so rounding issue when converting currencies I guess, the idea probably being to be equal to EU price but calculated in GBP), but for Weird West it was lower than even the US price, while for HoMM4 all 3 were equal.
EDIT: Checked the few actual games and one DLC from each game showing up on a catalog search for 0.79 EUR price at the moment, the large majority have a GB price of 0.99 EUR, but some have less, 0.69 or 0.59. None more than 0.99 though, but that's out of those that have 0.79 for me, there may be games with a different RO price than the more generic EU price.