What is wrong with this photo?

Quality issue I guess. You should submit the original asset that you did submit to Adobe stock, not a downscaled version of your picture. Most issues can't be detected on downscaled assets, and some problems that were not in the original asset get added.

You could enhance the contrast of your asset, you probably also need to liftt the shadows.

If you are new to stock, you should consider these resources: https://helpx.adobe.com/stock/contributor/tutorials.html
Please read the contributor user manual for more information on Adobe stock contributions: https://helpx.adobe.com/stock/contributor/user-guide.html
See here for rejection reasons: https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
and especially quality and technical issues: https://helpx.adobe.com/stock/contributor/help/quality-and-technical-issues.html

It does not appear to be in sharp focus, and the vertical elements are leaning.

I straightened the buildings, opened up the shadows in the foreground, and saturated the blue sky a bit. Those MIGHT be the issues. Difficult to tell these days.