After its big crossover with Star Trek: Lower Decks and before its musical episode, Star Trek: Strange New Worlds premieres one of the darkest episodes in series history. Season 2, Episode 8, "Under the Cloak of War" details the events of the Federation-Klingon War through extended flashback sequences. Several Enterprise crew members are veterans of the conflict, and the episode delves into their lingering trauma.
Source:https://www.cbr.com/star-trek-strange-new-worlds-mash-inspiration/