[Brightcolours]

Update on the "mRAW" and "sRAW". Apparently, Nikon has changed what that entails, on the D850.
 
Now, they are actually 12 bits "RAW".
 
Iliah Borg looks into the files with Raw digger and found that D850 RAW has 8,288 x 5,520 pixels in the RAW file. M has 7,104 x 4,728 pixels, S has 6,216 x 4,136 pixels.

Nikon RAW files get converted into 8,256 x 5,504 pixel images. (this always happens, many border pixels go *poof*).
The M ones get converted into 6,192 x 4,128 pixel images, some serious downsampling still going on there during conversion.
The S ones get converted into 4,128 x 2,752 pixel images, even more serious downsampling going on.

I am sure they have a reason for the 2nd downsampling during conversion. However, to me it seems to partly defeat the reason to shoot mRAW and sRAW (file size).