Although the proportions and shading are good, she almost looks a bit flat, notably in a few certain areas, for example, her toes.
The big elephant in the room are the outline corners. They're all rounded somewhat.
I believe you're using the line tool in a vector program like Flash/Animate (or something similar)
It doesn't look too bad when the lines are just 1-2 pixels wide, but at this resolution, (2160 x 3840 to be precise) it appears to be 4 pixels wide and I can see the roundedness and other imperfections.
Consider drawing the outlines using the brush tool, then tweak them a little bit afterward and allow sharper corners. In Flash/Animate, you can also "Convert Lines to Fills'
EDIT: I made no mention of that boot/sandal having unnecessary shading, but thanks for bringing that up.