The following forum buttons are very blurry in Firefox when set to 150% Full Zoom:

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And I assume any other buttons in this style.

https://imgur.com/a/oMEfR7Y

Regular text that isn't part of a picture is nice and crisp though.

It's been like this for years, mate.

Just ignore it. Bigger problems exist with this place than a couple of slightly blurry images.

Zoom is a feature of the web browser itself rather than of the website. When you zoom in, graphics are upscaled by the web browser most likely using bilinear upscaling in-browser, so any images will get upscaled from 1:1 to whatever the new zoom level is, which will potentially appear pixelated. The reason it is slightly blurry is an artifact of bilinear filtering that is a result of upscaling. It looks exactly the same in Google Chrome and probably any other web browser. It generally doesn't happen with fonts or SVG graphics as they are scalable vector based, so they are just rendered at a different scaling and can take the larger size into account.

Unless a graphic image/icon is an SVG however, it will result in visible pixelation and blurring artifacts from bilinear scale filtering. That's nothing specific to the GOG website however, the same is true on every website.

Why don't we try to be constructive here instead of mud slinging?

Sure, it is possible for GOG and every website on the web to replace all of their bitmapped graphics with SVG graphics for things like hand drawn icons, so that if they are zoomed in on they naturally upscale without pixelation. So technically this is possible.

But it isn't realistic to expect GOG or any other website to do this with all of their graphics either, especially for such a low priority minor issue when there are much more pressing matters that they could utilize their limited resources on. Browser feature induced blurry icons are the least of the GOG forum's shortcomings, no matter where one places the blame on why it occurs.

This problem seems like a prime candidate for someone who cares deeply about it to whip open Inkscape or their favourite SVG graphics software and recreate the icons as SVG images and submit them to GOG. Maybe they'll toss them a few free games or something.