This is due to the way white balance tools generally work in RAW file processors for DSLR/Mirrorless cameras. A lot of those algorithms do things that heighten the ends of the "color temperature scale"...the "cold" blue end and the "warm" red end. Color Temperature along the blue/yellow(/orange/red) is one of the key axes of white balance, while Color Tint along the green/magenta is the other. White balance tools can actually cause problems in terms of both temperature and tint...if you notice that you get a lot of purple, that would be a tint problem.
I would revert back to your camera's original white balance, and see what you get. You may be able to manually apply very small adjustments to temp and tint, or you might try one of the "standard" white balance settings, such as Daylight or Sunlight.
For my stuff, I use PixInsight to process, and for the most part I left things as the camera captured them, with the exception of neutralizing the background sky. I referenced a small patch of background sky devoid of any moon or its halo, and neutralized any color cast there. Where I could, I also referenced the exact same area of the moon with bright white areas as a white reference. So far, these have been my results:
This is with a Sony IMX071 sensor, which is actually fairly well known DSLR sensor used in some Nikon cameras (not sure if the D850 sensor is a Sony Exmor or Nikon sensor...if it is a Sony, then it should behave very much like the IMX071). I am not, so far, particularly liking the color of the red, but from a "white" standpoint so far just neutralizing the background has worked pretty well.
Edited by Jon Rista, 21 January 2019 - 10:14 PM.