I noticed that someone with new cs:go account was using an exploit on a server, freezing the server for 10-20 seconds, ping goes up from 5 to 80, after 1-2 minutes he get's timed out, is entering again on server and lag came again short time after. He got banned and no lag since then.
Only this message was in console: OGS PK VIOLATION: Dropping round data for round 0 session 2875184988692 because we've already submitted it.