The correct place to get feedback on your art is the WIP forum, not here. When your submission is rejected and the problem isn't something like "it's not pixel art", then that means you should improve the artwork, and that's what the WIP forum is for.

The problems I see are:

- The background is noisy. Is there a reason to have a noisy look instead of something tidy? It looks especially out of place since you use dithering on the face.

- The colours are low-contrast and hard to read, especially on the hair and halo. In addition, they're rather dull-looking because every object has the same hue for all its colours. If you change the hue progressively for each darker colour, the colours will look livelier. Hue-shifting like this also creates additional contrast without making the colours darker or lighter.

- The hair doesn't read well in general. Even with better colours, it's unclear what the forms are, how things are attached, etc.

- The hair and halo have a lot of banding, which is when pixels/lines of different colours line up exactly, creating "fat" lines/pixels and making the image look blocky.

While I doubt any one of these would cause your work to be rejected, the combination of them very likely would.