Every day that i log i report the mmr selling bots while i queue for labyrinth.
Today i log and found that am muted for disruptive behavior for 300 hours on public channels, i can still chat/voice normally in game since i am not disruptive or have negative behaviour score.

Last year i also experienced the same thing right around the this time a random 10 day mute for no reason. Only thing that comes to mind is that i report mmr sellign bots.