Punishment leniency and warnings.
I use negative chat in game. I get reported after game. The IFS saves the game but does not punish or notify me.
At this point, the chat offender has no idea they just broke the rules. The chat offender may even think they were being positive.
This is why warnings are so important. Pure warnings. We are big kids. We use our words. NO CHAT RESTRICTION WITH THE WARNING.
However, if warnings just aren't your jam; punishment leniency is still a bad idea. A non-punished behavior is likely to continue. If that behavior continues long enough, it may even become habit. Riots system is creating habitually toxic people.