Ugh >/ Why did it mess up?! - The PokéCommunity Forums

;_; Damn.. it's pixellated here..

Th-that's a doodle?! xD That's amazing.. ; ;

The term is artifacted, for future reference. As for why it came to be like that: High quality JPEGs tend to be bigger even than PNGs, and images of a certain filesize get resaved just as those with overly large dimensions do.