Bravo confirmed that they didn't plan to fire Hannah Ferrier for drug possession from the get-go. The vice-president came forward to assuage these fears about Below Deck Med. While Ferrier claimed that she was quitting due to being pregnant, viewers quickly learned the real reason she wasn't setting sail with Captain Sandy and the others.
Before the episode aired, Ferrier maintained that she was on maternity leave. She has been handling her ongoing pregnancy with grace. We find out that for legal reasons, Captain Sandy had to fire Ferrier after crew member Malia reported that the chef had smuggled a vape pen and prescription Valium onto the yacht. As Sandy put it, the issue is that Ferrier lied about it; she would have been fine if she had notified her captain and the safety officer. She doesn't want a crew member endangering the guests while under the influence. The lies also destroy morale on the ship.
Some viewers expressed the suspicion that Ferrier's firing was an excuse to replace her with Malia's boyfriend in terms of cooking. An executive confirmed with Cheat Sheet that this was not the case; Bravo VP Josh Brown explains that, practically speaking, you don't want to let go of your staff in the middle of filming. Ferrier was a longstanding crew member and despite her contentions with others, she was appreciated and loved. Her firing disrupted the schedule for filming and emotional balance on the ship.
Given the rules required for yachts and charter vessels, it's no surprise that Captain Sandy had to fire Ferrier. Former crew members agree as much, some with captain positions and licenses. Disclosing drugs and registering them with the safety officer or the captain is absolutely necessary to ensure that the crew complies with the law and that the passengers are safe. Otherwise, Sandy could lose her license and credibility.
Was this unscripted? More than likely, for the reasons that Brown mentioned. Ferrier has been a controversial figure before, due to her abrasive nature and conflicts with other crew members; she and Captain Sandy have had various spats. Even so, she is good at her job; it took a potential legal offense for her to lose her job. Fans will miss her, and time will tell how season five goes.
Source: Cheat Sheet