This is such an awesome Vector! Very clean and smooth lineart.
If I could make any suggestions or offer any advice it would be to maybe
consider adding some bubbles around her or deepen the bottom of the wallpaper while
highlighting the top to show more of a depth in the water and contrast. For example rather than
dark all around it's more of a light to dark look, lighting could use a few tweaks to help it look more
realistic
like with Sakura's hair, rather than having it all illuminated only the hair where her feather shines would've
been a nicer touch.
Also some sparkles around the feather to help signify how magical and important they are :)
Overall a super wonderful job! Love to see more :3