Idea

Could have been an episode of the Picard show. The idea is that it turns out that Ensign Sito from the Lower Decks episode wasn't really killed, but was actually just taken prisoner and the Cardassians made it look like she was killed in her escape pod. So over the last couple of decades, she had to endure what Picard was threatened with in Chain of Command if he hadn't been released. Now she has either been conditioned by Cardassians and is under their control, or maybe she is just pissed at Starfleet because the Cardassian she was helping ended up betraying her to save himself or family or something. This ideas has probably already been fan fiction somewhere, I'm sure.