The Warlock Invocation Devil's Sight (PHB p108) is described like this:
You can see normally in darkness, both magical and nonmagical, to a distance of 120 feet.
How should this be interpreted, given the undefined use of the word "normally" and the description of a real devil's Devil's Sight ability?
Barbed Devil (MM p.70):
Magical darkness doesn't impede the devil's darkvision