Mix sounds good to me, but am I hearing weird distorted reverb from the snare drum? prominent at beginning? This alone could warrant a reject. Sounds like the snare wires decided to turn 8-bit on the decay, but probably just a cheap plate/spring reverb? Doesn’t suit the track, IMO. It doesn’t really stand out on the rest of the track, but the first two measures with just drums and claps it is quite noticeable.
As far as high frequency sound, a lot of the mixes on this site sound too bass-heavy/muffled to me. Maybe that comes through better on cheap headphones, but through my equipment that kind of mix style doesn’t sound great. I think in most applications outside of Audio Jungle, people prefer a more “mid” sound, but here everyone goes nuts for low/low-mid frequencies. That being said, I would have brought up the bass slightly in the mix, and the bass sound also sounds a bit canned. But these are quibbles - I wouldn’t have rejected the track for the mix, but for the weird reverb.