The answer to this is almost always no. Your Firefox data is stored in your profile folder. Reinstalling doesn't affect that, so you'll start off with the same add-ons, modified preferences, cache and cookies, and therefore the same problems as well.

To try out a fresh start without affecting your current data, type about:profiles into the address bar and create a new profile there. Note that doing so will automatically set it as the default, so click the Set as Default button below your original profile right away. Then sign out of GOG in your regular profile, and click the Launch Profile in New Browser button below the new profile to try things out there. You might be sent a 2FA code via e-mail that you'll have to type out, so be sure you still have access to that account beforehand.
Without any add-ons and with all settings at default, the only browser feature that's likely to interfere is Enhanced Tracking Protection. You can check the settings for that under about:preferences#privacy or you can click the shield icon on the left side of the address bar.

So, to report back: totally fresh install of Firefox with no add-ons and GOG store page simply doesn't work.

Right now, it shows me, that there are games and DLCs on sale trought 3 pages, but, cannot click on page 2, also the only button, that works is the green cart button.

I also tried to filter (like checked action, adventure etc.), but without any effects.

Most images doesn't load either.

I included some screenshots and will try to make a short GIF video.

I am writing this post from MS Edge browser.

Oh, and I forgot: I deleted the whole Mozilla folder inside C:\Users\(profilename)\AppData\Roaming\

I have the same problems. The site does not work anymore with firefox.

And Microsoft Edge is not better at all. Here the site has the same problems with missing graphics, not being able to change sale pages and so on. Something is VERY borked here.

EDIT: google chrome is borked, too. NEW installation! So the error must be at GOGs side...

Everything seems to be working fine here. (That is, the shiny new catalogue search page seems to be working as intended, and nothing else is more broken than usual.)
Win 8, Firefox 96.0.3, just a handful of extensions enabled (only one in common with OP's list is AbP, which I do have enabled on GOG).

1. Double-check your HOSTS file. If all lines begin with the # character, then there's nothing blocked there.
2. This is highly unlikely, but maybe also go to about:preferences in Firefox and double-check your proxy settings. If you don't need a proxy to connect, make sure "No Proxy" is selected.
3. While you're there, also check "Enable DNS over HTTPS" with the default provider, Cloudflare.
4. Once that's done, press Ctrl+Shift+R while on the GOG catalog page to reload it without the cache.

Other than that, I don't know what could be wrong.
• I have Enhanced Tracking Protection enabled and it's not causing me any issues.
• If any of the bundled Firefox add-ons were causing problems, there would be a lot more reports on the forum.
• Windows Defender and Windows Firewall are very permissive and unlikely to cause issues.
• If there was an issue with the GOG servers, another browser would have the same problems.

Same for me, when I use the page in English. But when I switch to a different language like German or French, it works.

WTF GOG? You are right.

When I switch to german (I do not want to do that here) everything is as it should be.

How did they do that crap? NOW we are talking about levels of "page not useable"...

Yes, you are right! I am using Firefox in Slovenian language, Edge too and using the English GOG store page

If I switch the GOG website to other language (tried German) it works more or less. I mean the Store page.


Included two screenshots -> and I am not even signed in!!! (•_•)

OK, I have some news... I was away and after about 1 Hour later, I tried to relaod the GOG Store page and it doesn't work anymore in German too... tried to switch back to English, French etc. and it is simply broken in Firefox . I included a new screenshot.

My configuration:
AMD Ryzen 5600G with Radeon VEGA 7
32 GB RAM
1 TB SSD
Windows 10 Home 64-bit, 21H2

...

Funnily enough i use it in English and it works splendidly - from what you and others told us in this thread kinda afraid though to change to another language as i feel it might break it

I can confirm there were some issues earlier in the day, but everything seems to be working fine now.

Now it works. Something was wrong in the last 24 hours or so. Thanks to GOG Team for fixing it.

Glad to hear its working again!