This happens to me a lot. My pictures get rejected because of quality issues. I dont see why. Good resolution, no grain or artefacts to my eyes. And I think its sharp enough. Maybe becuase of the flare?
Shutterstock appeals to a different customer base with lower requirements.
Adobe Stock customers expect the highest visual and technical quality for use in commercial projects. As a customer, I could not use any of these images. The quality is not high enough for professional print process. Read these links.