Mythic Players are reporting a "concede bug" on Magic Arena
According to Shaun (Team AUS) and other players on Twitter, they lost ranks on the ranked ladder after they won and their opponent has conceded the game
Image Credits: Wizards of the Coast
Cards Realm
The bug has been around for over a month now. According to Hareeb al-Saq, conceding a Best-of-Three match during the Sideboard may cause a forced Draw, causing players to lose ranked points
Image Credits: Wizards of the Coast
The highest ranked player may then lose up to 100 ranks!
Cards Realm
Player u/altheriax on Reddit has suggested that server enforced draws should not affect the players' rank, but we have no official statement for now