Card images since MID are lower quality and the file sizes are much larger
Ever since the release of Midnight Hunt, the images that appear in Companion are considerably more pixelated than from Ixalan foward, and they load a -lot- slower over cellular.
It took me a while to figure it out, but I think it's because instead of being JPGs (with white corners), they are now much larger PNG files (with rounded corners). Digging around on my phone seems to show that each image has gone from being crystal clear at ~200KB to being pixelated and harder to read at ~800KB.
Consider going back to JPEG and rounding in Companion or switching to something like WebP which gives you the best of all worlds.