Extra Utilities 2 (at least in version 1.12.2) screens are no longer capable of fetching and rendering images hosted on Imgur.
This was extensively tested in singleplayer and multiplayer instances, with a variety of images well below 255kb in size, and any form of rate-limiting has also been ruled out as far as my testing goes. I believe changes made by Imgur are the culprit.

Extra Utilities 2 itself is no longer developed, and its screens and the code behind it are entirely hardcoded around using Imgur.
It would be great to see a workaround that allows for EU2 screens to use custom hosts much like MrCrayFish's TVs allow you to define/whitelist hosts from which to fetch images.