Please do not let In-Client Warnings trigger until the player leaves post game chat
Basically, we had this Leona who pretty much QQed all game. After the game she got a popup warning saying she had been reported for Negative Attitude. She knew it was one of us so she flamed us and said she would report everyone if one of us didn't confess about reporting her. So, no one confessed, and she reported all 9 players. I got a warning for Offensive Language when I rarely even chatted in the game.
Please prevent false reports from trigger warnings (yes, many of my friends have confirmed that sometimes the warning will trigger on false reports) and also don't let one pop up on a player's screen until they have left Post Game. Otherwise people just get pissed and revenge report other players.