Many Valorant players have complained about multiple bugs at the end of their ranked. They were apparently demoted quite aggressively by the game when they lost a game.
Knowing that the competitive mode has only been available for a short time, Riot Games reacted quickly by communicating on social networks to reassure players and announce that a fix would be deployed.
The issue was quickly resolved and for players who were impacted, all they had to do was win a game to regain their original rank. This is reminiscent of the episode where a bug affected Reyna on Haven. Developers reacted quickly enough by removing the map from the pool to fix it.