Nebula popped up a few times during Infinity War, starting with being tortured by Thanos during the film’s second act. She was once again hurt by her father Thanos, and used to coercing Gamora into revealing the Soul Stone’s location. The blue badass eventually returned during the epic Battle on Titan, dropping a truth bomb on Peter Quill that would ruin their chance at beating Thanos. Ultimately she survived the snap, and was left stranded on the desolate planet with Tony Stark.
Article source: https://www.cinemablend.com/news/2465295/avengers-endgame-reshoots-are-in-full-swing