Today on 12/1 I also experienced a similar bug. If at most I have only left 1 game in my accounts lifespan of 200+ games. Although today my internet connection dropped for about 5 - 7 minutes. Once my connection was restored and I received a steam error while booting deadlock and had no option to rejoin my match. I restarted steam, rebooted deadlock and was able to rejoin the game. We finished out the match and was gifted with a 2 hour ban.
I understand things happen but I hope this helps if possible. It seemed if there may be a client side issue with a mirrored connection. As if i couldn't connect because i was still "in the game"