When I come across images that take up more than my screen space, they are always blurry. Even opening the image and zooming, they will be blurry. I can download them and the quality is normal.
If you open it and hit the "HD" button up at the top right
I vaguely remember an option to make them load the full images by default in the reddit version, but i could be mis remembering
It's not exactly a bug, this is how it's always been. You're loading the thumbnail in the feed, not the actual whole image. Some images around here are 20+ mbs