Edited image appears okay in Develop Mode but pixelated in Library Mode

So, I've just edited a raw image in LrC. The photo looks fine when i see it in Develop Mode but once I go into Library Mode the photo appears pixelated. This has never happened to me before and it doesn't happen with other edited photos. I don't know if it has something to do with how I edited it (although I edited the photo as any other) or something else. Any ideas?

Here are both images as seen from my mac, the first one is as seen in Develop Mode and the second one as seen in Library Mode.