Update: Ignore the rest of the comment. I just tried to request the image with any User-Agent and it’s now always serving the full resolution image. It definitely wasn’t returning the full resolution images the last time I tried even with different User-Agents for Chrome/Firefox/etc. My leading theory is this image host just sucks.

Old

This is very interesting. The story continues.

I see that two uses have reported that the image loads fine on two different Lemmy clients. This told me this is unlikely to be a coincidence. So I double checked the image in Thunder and like you’ve both reported the image loads as expected.

Then I figured out that Voyager and Thunder share one thing in common: they are both built using Flutter.

From my previous test I knew that the image host (postimg.cc) is using the user agent and other clues to serve different content to different browsers/apps. So my next theory is that the image host serves raws to flutter clients.

To test this theory I looked up the default user agent of Flutter apps which is just Flutter-version, then I looked up the latest version of flutter which is 3.71. Then I tried making a request to the url with User-Agent Dart/3.7.1 and boom the website returned the full 3.71MB raw for the image solving the mystery.

As a fix for clients (and this is a terrible terrible fix) any app that wants to get raws off this host needs to send their request with a Flutter user agent.