it’s not a question of difficulty lol, it’s simply a question of “if you zoom in you’ll notice that the ‘pixels’ you’re seeing aren’t actually pixels”. For comparison, you can try zooming in on the work of an actual pro pixel artist and see how clear the pixel grid is at high scales.
This kind of result does not happen in a normal pixel art workflow, regardless of skill level, but is an extremely common output of diffusion models. Hence my original comment.