Avengers: Endgame saw both The Hulk and Iron Man unleash the power of the Infinity Stones, but Nebula was never given that chance. In the Infinity Gauntlet comic book, Nebula used it to restore her original appearance and to defeat the Mad Titan, so why was that moment taken from her in the Marvel Cinematic Universe?
Well, during a live commentary for the film last night, Avengers: Infinity War and Endgame writer Christopher Markus explained to a fan that while, "It was in the script for a while...it undercut the weight of Tony putting it on."
It seems Iron Man was always destined to die while using the Infinity Gauntlet to put an end to Thanos, and Nebula making use of it to restore her appearance (and survive) probably wouldn't have made much sense in the wider context of the movie. Still, it would have been cool to see, and given Karen Gillan the opportunity to appear without all those prosthetics moving forward!
Heading into Guardians of the Galaxy Vol. 3, Nebula will have to deal with the aftermath of Avengers: Endgame, and attempt to reach out to her sister (who has no memories beyond 2014).
Check out Markus' comments below: