Update: Riot has now disabled Haven in Ranked.
A new Valorant exploit has been discovered on Haven that is absolutely game-breaking.
Redditor, TwaiseReddit, shared the clip that shows Reyna using her Dismiss ability to get inside the platform at C site by crouching and moving into it.
Reyna is able to stay inside the box and wall bang enemies through it. She can even plant the spike inside the box, making it impossible to reach for a defuse.
The only counter right now is a Reyna of your own to exploit inside there or a lucky wall bang.
Riot will almost certainly patch this exploit out soon, but for now, it still works on live servers so look out for it in your Ranked games.