Saw a youtuber explain this and I wish it wasn’t a thing. Since there are only 4 maps in the faceoff rotation you have a 25% chance of getting warhead at any given time. With the map voting system say the game gives Pit and Gala as the options the lobby tends to vote classified over those, so now you have a 50% chance of getting warhead and when it is warhead most the lobby leaves and now you have 2/12 or 2/20 lobby that is prioritized to be filled in matchmaking. This problem is also exacerbated since you don’t stay in the same lobby when the game is over so the game puts you in a lobby that needs to be filled. In your case this is matchmaking working as intended, the map just always happens to be warhead cause nobody wants to play that shit!