This is the same issue as: Randomly kicked from game and given loss during draft reported here: https://feedback.wizards.com/forums/918667-mtg-arena-bugs-product-suggestions/suggestions/49042190-randomly-kicked-from-game-and-given-loss-during-dr. My second round game just kicked me back to the main menu in the middle of the game, and after i played and lost the next game, i had 3 losses instead of 2 despite only completing two games.