There are times when your personal choices may need to take a backseat to more important goals. If you are really committed to a mission, even one you've decided to leave, I would think you'd want to give feedback that can help improve the chances of that mission being successful, even if there's a personal downside risk.
Think about something like the Boeing 737-MAX. Imagine a software engineer who decides to leave because they think the safety culture is really terrible. Would you prefer that employee voice their opinion during exit, despite the chances that it may make a change, or just quietly slip out the back?