The new Design / UX agreed default color for NPC is RGB #268bd2 named
This clip shows that compared to the existing unnamed blue used for NPC with
RGB #6abed3 as implemented in bug 68071
As a default, the new blue is a bit more pronounced on both light and darker
When the enhancement for a Tools -> Options -> Appearance -> Custom Colors
control of the NPC variable NON_PRINTING_CHARACTER_COLOR RGB_COLORDATA can be
implemented this color as default should be completely functional.