Image rejected for artifacts problem?

This image I uploaded was rejected for "artifacts problem", which is described as being caused by "low light, bad camera settings, strong compression or excessive post-production." Looking at this image, I don't really see any of these issues. There is almost no noise or compression, the exposure seems fine, and the post-processing I did on the image was the fairly basic adjustments that you do to make a raw image pop.
If anyone could give me some feedback as to why it was rejected, I would appreciate it.
