It may well be that dPreview has used a
pre-production model of the Z7. I have the impression that Nikon has at an early stage released cameras that were not quite up to date with the final production models. Possibly. was that such a model. Otherwise, I can not explain that some cameras have such a banding and others, like mine, not. What I also noticed: in the pre-production model, which I tested very early, I could with a trickedit the RAW files from the
Z7 in Lightroom, namely by declaring them as D850 images. This works with the RAW files from my current Z7 (production model) no longer. It seems to have done so in the RAW files still a lot on the last minute.
But again: these are absolute extreme tests under quite artificial conditions - in practice you will see in 99.9% of all images
no difference between images from the Z7 and D850. But it's nice to see that in the extreme areas of the Z7 sensor could even grow a little bit and despite the fact that now also the phase AF is housed on the sensor.