My friends and I 5 stacked in a ranked game, we won 4-0 but when we went back to the menu we all received a ban and lost 150 MMR each.
Hello BaIIstein, thanks for posting about this and sorry to hear this.
What platform do you play on and what did the ban message say exactly? Can I also ask how long the amount of time the ban was for?
Did you also notice any of your team mates having ping issues in the game and did everyone stay in a a team until after the results screen as renown screen was shown or is this when the ban message came up for you?
Finally can I ask if anyone on your team had to re-join the match when it was in progress after disconnecting?