I'm just concerned about recent stuff, it's nothing much.
Your pixel's head, the face is pillowy shaded a little, you've used many similar shades in darker colors on some parts on the pixel, dress and hair to be specific, you need to limit colors when you're doing pixels (unless you're not going for a specific color count)
I dunno how to explain it better, the multiple shades might've been from you using SAI or w/e you use for colors, might've been a brush tool instead of a pencil tool.