what is my mistake?
What were the reasons Adobe gave in their rejection notice? They always state the reason.
My guess is that the rejection reason they state is "Exposure issues".
I see a slight amount of banding above the horizon, left of the lighting, especially in the transition from the darkest tone.
Some bending (as already mentioned), horizon is not horizontal and artefacts in the lower (dark) part of the image (pop up the brightness to see them).
While lightning is very cool aesthetically, the positioning of this lightning is strange (I know you can't predict where it'll hit). But it's not centered and not further to the right to leave room for copy. Plus the lack of foreground detail adds to the lack of Aesthetics.
Plus the banding and the overall exposure like mentioned above