Personal experience: I have found that rendering anything dark (like an evening/night sky) generally results in colour banding. For instance, in this image:

http://www.renderosity.com/mod/gallery/index.php?image_id=2174093&user_id=362711&np&np

...I rendered the sky (skydome by Bagginsbill) and water separately using full-light (like, daylight) settings, then photoshopped it to this current darker state. Not sure if it's a Poser-specific problem, but the renders were unacceptable when rendering sky and water with the foreground.

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks