Film something like that again and go down to 1080 60fps..I think you will see a remarkable difference. As mentioned it's all about light and the amount of info you cram in there for encoding. I also think that DJI editor is causing some of it. I used Windows default editor and it did the very same thing on a much clearer video, when I went to a "real" editor and encoded it it was all crystal clear when I viewed it.
Does your view on your computer (Straight from the SDCard) look anything like that? I am guessing it doesn't.