warum wurde dieses bild abgelehnt?

I also see legal issues related to IP.  

• https://helpx.adobe.com/stock/contributor/submit-your-content/submit-photos/technical-legal-requirements-photo-submission.html
• https://helpx.adobe.com/in/stock/contributor/help/known-image-restrictions.html

When taking such shots, be careful of objects such as this:

This corner could be corrected as well, in case you re-submit.

There is some slight highlight clipping.
Images may be rejected if there is blown-out highlight detail or crushed blacks.

Even if that is corrected, the image would still be rejected because a person's face is visible.
If a person's face is recognizable, a model release is required.

Your cropping is way too tight for usage, also the identifiable people on the bottom left another cause for rejection.

Keep in mind this is just another Trevi fountain shot, if you’re traveling with someone ALWAYS add a human element to your stock pictures… “tourist taking photo of Trevi Fountain” using a mode release occurs!

Have a great day!