Hi,
the picture shows strong noise in the sky and the birds don't seem to be really sharp. Seams around the contours are also visible. These are definitely technical problems that lead to rejection by Adobe. If another agency accepts such pictures, it is not technically understandable, I mean. But each agency has its own level of quality here, but I don't think it fits the quality standards of Adobe Stock. Here you should pay more attention to the technical requirements for an upload and acceptance of images by Adobe. The User Guide for Adobe vendors provides helpful information here.
Greets,
v.poth