I don't have a problem with rejections except on Wirestock. They hit me for "composition"
So I just ignore them and move on.
I think Shutterstock uses an AI for it's initial culling and anything that looks a bit strange gets kicked out.
Sandstorms are rejected for grain. Yep, that's the stupid AI not knowing sand from noise.
The sharply in focus part of the image needs to be in the center of the image else the AI might not find it.
Stock is stock and not art, so you just have to play the game.