I'm using an up-to-date Firefox in Privacy Mode when I'm on GOG (meaning all extensions are turned off by default, to avoid conflicts). And, I also switched off the Advanced Tracking Protection when on GOG, otherwise I can't log in.

Everything works fine. Main store front loads correctly, including all images. All Browse Deals buttons lead me to pages that load correctly. All pages announcing new releases and all pages stemming from News also load perfectly. No trouble with forum pages and personal pages, such as wishlists and order history.

But, whenever I click on an individual game, Firefox takes me to that game's page and it is completely blank! The url appears correct. No error messages. Just a blank page. It's very strange... Nowhere else on the internet do I encounter this issue! Only here on GOG! :(

Here are some specific examples...

When I click on the Age of Wonders 4 banner on the front page under the Highlights section, I get a blank page:
https://www.gog.com/en/game/age_of_wonders_4_archon_prophecy

Also, when I click on the Gex Trilogy banner on the front page under the Highlights section, I am presented with a blank page:
https://www.gog.com/en/game/gex_trilogy

Again, from the front store page, at the very bottom in the News section, when I click on the Release: Dark Deity 2 with Soundtrack banner, it takes me to the Release page details and everything loads fine, including the embedded Youtube video:
https://www.gog.com/en/news/release_dark_deity_2_with_soundtrack_and_deluxe_edition

But, when I click on the link for the game page itself, it's completely blank!
https://www.gog.com/en/game/dark_deity_2

I tested Firefox both in default mode (with all extensions activated) and in Privacy Mode (with all extensions turned off) and I get the exact same results. Individual game pages load completely blank.

Very frustrating! I'm at a loss. Never, ever experienced this while browsing outside of GOG.

If anyone has any suggestions to share or if anyone can shed some light on issues I may have overlooked, please do! :) I'd appreciate any help that is offered.

Thanks in advance!

No issue, no issue, no issue, no issue. I'd open the developer console/inspector mode, switch to the network tab, and start there to see if there's any blocked requests or failed service.

Currently I can't get any GOG pages to load correctly in Firefox (this includes Games Library, Wishlist and General Discussion Forum).

However, they do load OK in Pale Moon.

Thanks for the posts, everyone! It was late last night when I noticed this issue. Now it's 10h30 in the morning and everything seems back to normal. Quite weird. I'm off to work soon, but I'll keep an eye on this when I get back later tonight. Thanks for the developer console advise! I forgot about this Firefox feature. I'll check it out! :) I appreciate your many angles of approach! I get the impression you're quite the debugger. ;) If the problem comes back, I'll definitely verify with another browser to see if I can duplicate the error. Thanks for confirming what dnovraD suggested. When I'm in Private Mode, my uBlock Origin is deactivated and when in default mode, it is turned on, but in either case, the problem manifested. I do have Firefox on my smartphone and I did not think about testing it that way! My router and firewall have never caused this issue on GOG before or even for any other website, but thanks for bringing those up. If the problem happens again, you've given me so many options to verify. Much appreciated!

It seems like the issue has not repeated itself tonight. Safe to assume what happened to me was simply a one-off? Someone suggested to me via chat that maybe GOG might be prepping their servers for the upcoming Summer Sale and I happened upon a glitch of sorts?

In any and all cases, thank you dnovraD and gogtrial34987 for your help and advice and very useful information. :)

Yeah, I've witnessed a few others. Maybe note it down in the "what broke now" thread; mentioning of course that it resolved, but you can give times if you'd like for future noting.

Having the same issue. Some pages for games always result in a crash on Firefox. For example this page always leads to a tab crash, even in a private window or after clearing all cache:

https://www.gog.com/en/game/heroes_of_might_and_magic_iii_horn_of_the_abyss

I can only access it on the gog galaxy launcher.
Installing Chrome is not a valid workaround. I don't want that spyware ridden Google crap.

That page features an auto-playing MP4 (video file) and an animated GIF.

The GIF would not cause problems, but, due to issues with video hardware acceleration, the auto-playing MP4 might be a potential culprit. In the past, on older hardware (with poorly supported integrated graphics), it had been necessary to adjust some about:config parameters within Firefox. This had been quite long ago, but, it may have involved toggling the options for media.hardware-video-decoding.enabled and/or media.navigator.mediadatadecoder_h264_enabled -- again, uncertain.