I think the reason for the hard reject is that the design feels a bit too basic 
. Maybe try to spice up the typography and make the fonts pop a bit more? The colors also look a bit flat, so you could add some depth or contrast. Also, the image quality doesn’t quite match the vibe, so maybe use higher-quality pictures or try something more creative with the image.
Check out some of the top flyers on Envato to get a feel for what’s working, and keep improving from there! You’ve got this!