Blurry/grainy cover title pictures

[Centsiclesss]

Hello,for some reason covers look really blurry/grainy. It looks blurry sometimes when you get it from an extension,but if you get it from your file directory its all pixelated. In the image the very top left one is from an extension and its blurry,the one next to it is an odd case,its not blurry even though i got it from an extension. The one in the very far right is the one i downloaded,its looks really grainy. Thanks!

P.S i noticed that if you are not in full screen it doesnt seem as blurry,but its really annoying not to be in full scree

edit: Wrong category to post this in,i posted it in issues now,sorry