picture was rejected for technical issues. What are some ways to improve the picture?

Monochrome conversions are not accepted by Adobe Stock. Zoom in to the sky and you'll see some bizarre pink artifacts. The composition needs work. At the very least, straighten the verticals.   But even if you fix those issues, I'm not certain that this type of image has any commercial appeal - try to imagine how a client would utilize this on their website or marketing materials...