That's what I call "codec noise", sadly a known and hard (if possible) to avoid issue with canon VDSLR. Things that might help :
- using an on camera "flat" color profile like flaat10.
- lowering contrast, saturation and sharpening on this profile (the guy behing flaat10 provide good guidelines for his profiles).
- disabling every picture processing options like "highlight priority".
- staying away from the exposure zone were the issue is most visible, ie better plan your lighting and exposure. Being outdoor with a nice sun at 100 iso won't matter if you're shooting people standing in a shadow area with dark clothes. Keep in mind that with this kind of camera you have a very limited dynamic range to work with. Shadow + sunlight will give you nothing but overexposed highlights and muddy shadows.
- not doing the post work in native H264 but rather transcode to something like DNxHD or ProRes (that was usefull with FCP7 and Color, I have no idea how Premiere handle this, never tested and probably never will).
- not letting this drive you crazy. It's quite hard to see in your video and I probably only saw it because I knew what you were talking about before I even watched the video. It is highly improbable that most viewer will notice it.