Random Reports, without any reasons

Hi Everyone

Recently, after some normal games (still unranked, new acc), i got random reports for verbal abuse/bad behaviour and a window showed up, i shouldnt do this anymore. The problem is, im not avare of verbal abuse or bad behaviour, i dont write too much and i dont try to annoy my mates or enemies. Often i get those reports after we lost a game and i think one allie just got mad and reported everyone for no reason. So: How does Riot know if those reports accord to the truth or if they are just the result of a moody player who wants to annoy someone by reporting randomly?? Now i got a chat restriction for nothing.....pretty annoying...