The last match I played was on November 3.
I log in now to see that I've been restricted from communications (and subsequently, cannot play competitive) until November 12.
Customer support's response was that I had received a large number of reports (?) (despite not using VOIP and rarely text chat to say "gg") and were therefore banned. No logs. No evidence.
What caused the system to randomly give me a 9 day ban while not playing for over a week?