Whay could be the reason for rejection?

OMG. They are becoming more and more critical :0(

Sorry, I forgot to includ this.

This would have passed a few months ago when Adobe first began accepting AI but they are becoming much more stringent with regard to AI submissions. View this image at 200% or even 300%. Note that the pupils of the eys do not look realistic. Also, there are roughly rendered hairs in the corners of the image. I would recommend that you take advantage of facial restoration software to fix the eyes (Google facial restoration software and you'll find a few options available). Also, if you are going to get serious about submitting photorealistic portraits on a regular basis, I strongly recommend that you purchase PortraitPro Studio, which I use regularly to soften hair. For roughly drawn hair or flyaway hairs, use of the Clone, Remove, and Content Aware tools. Generative Fill can also come in handy to replace sections of hair that are poorly drawn compared to the rest of the hair overall.

Over time, you might get lucky and come up with some rendered portraits where the eyes get drawn perfectly. Copy and save them to your Library and use them to replace irises that are less than perfect in future renders. Green eyes, brown eyes, blue eyes, etc.

In my opinion it is the hair and the eyelids. There is hair on the lower right side over her shoulder that is not connected to her head. On the left and right side is hair that is going in the wrong direction. Her upper eyelids  all appear cut off.

Also the bottom of her chin is not drawn, and there are no details in her neck.