Don't even bother. GOG has long ago abandoned any kind of sense in regional pricing. They used to have a "fair price" policy but it was ended years ago. Since then I stopped buying anything at GOG as their prices are atrocious compared to any other game store front in the world. Especially since GOG also abandoned their stance on DRM, introducing it even into their flagship products like Witcher 3 and Cyberpunk, makes 0 sense to pay extra to buy them here and still get DRM-locked content. I'd rather pay less on steam and save money.

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.

doesn't apply to this thread either or even GOG in general. GOG regional pricing follows it's own standards, wildly different from pretty much any other game storefront globally. Yes, publishers set their 'matrix' but GOG prices on vast majority of games doesn't follow it, or vary according to GOG's own 'matrix', because while game prices would be similar on any other game store (steam/ubi/ea/epic), GOG prices are much, much higher in many regions/countries. Just read this thread going back years, when GOG abandoned 'fair pricing' policy. Buyers from south america, asia, etc complain that in their country's currency prices are much higher than steam or any other given storefront, all on the same game. There are few exceptions, US, most EU countries (not all), Russia, China maybe, basically large/huge gaming markets where following general pricing trend is beneficial but many other smaller markets (and some big, like someone from Brazil complained a while ago) are not treated as very profitable, so the prices are increased way beyond what any other game store charges there, and, as such, it doesn't appear the 'publisher matrix' is followed all that closely in many countries of the world by GOG. As a matter of fact, I've personally noticed some sudden prices increases in my country in GOG on a particular game (for example from $25 to $30) when none of it happens anywhere else. If it was a publisher raising prices for my country, don't you think the price would've gone up in steam or epic as well? well, it didn't, and it's been a few years since that occurred.

Publishers always set the prices, stores only may make recommendations. One thing that is possible is that exceptions happen when the store does not support a certain region or currency. If a store doesn't support separate pricing for a certain region, obviously that region gets the standard (US) price. If it doesn't support that region's currency, obviously the publisher can't set a price in that currency and may choose to just skip it, leaving the standard price for it, or convert to a supported currency for that region, probably USD, which means that the prices in that region will change with every exchange rate change (making this bit relevant for this topic). This latter scenario will lead to what you said, if your currency isn't supported (see the blue posts in this thread for the supported ones), prices changing just on GOG and not on another store that does support it.
Also, those complaints all come from people from regions that usually get massive discounts, so it's not a case of price increases, like those from the EU usually get all the time (including the poorer EU countries, and typically even non-EU Serbia and Montenegro), but of seeing what the standard price is instead of a discounted one.

No, EU laws demand that taxes are already included in the price.

GB is not part of the EU anymore, so it can't be part of the same price scheme.

Sorry but that's not my experience, or the experience of a number of other users in this thread for several years across the globe, just go back a few pages and read numerous complaints to that end. GOG prices exceed abnormally the prices of other storefronts, and frequently in local currency. You may be right for other stores but GOG is certainly doing things its own way.
Also, your explanation is wrong, I am not getting US price, it's still regional but hiked up without being mirrored in other stores. You are also wrong about everyone else, they complain about abnormally high prices for their country specifically at GOG. But whatever, if you wish to remain obtuse or willfully ignorant, that's your choice, your beliefs do not change the reality for thousands, if not millions of GOG users.

Give some examples of games that have higher-than-US prices in regions that normally get lower ones, and yours in particular if you'll say what that is, and I'll stand corrected. With nothing else to go on at the moment, checked PS:T EE, mentioned by caiman earlier, and see $19.99 US price, $7.45 in Latin America but the same $19.99 in countries like Turkey, Indonesia, Malaysia or India, which might be used to discounts on other stores.

I'm done arguing with you, I've said all I needed to say and you keep being deliberately obtuse.

using same link, my friend and me are both in france, but I have to pay 11€ more. (screen in attachement)

of course with this price I take it on steam instead...

That'd really be a geolocation fail on GOG's part then, as 71.99 EUR is the price for Switzerland. You should complain to GOG and have them sort it out.

Steam all the way.

I apologize for the confusion. In the UK taxi fares typically include a 20% VAT (Value-Added Tax) rate, which is reflected in the price listed. However, if the European price is without tax, it must be adjusted upwards by around 50% at checkout to match the UK price once taxes are applied. But, as you mentioned, EU laws require that taxes be included in the advertised price, so it's unlikely that there would be such a large discrepancy between the two prices.

Didn't say it was about taxes anyway (in my case it's 23% or 25% taxes). What I said is that UK is not in the EU anymore, so the prices in UK can be higher or lower. One World One Price was a long time ago. Publishers didn't like it.