i was told in a recent conversation with riot support member that if you report the person and state in the comments when and why you are reporting the player they will look at post game chat if that is the case ( or pre game chat if that is the case )
Mama Meep (Riot Games Player Support)
Sep 9, 11:11 AM PDT
Hey there,
If players are using post game lobby to abuse others, then simply note that in the comment of your report so we can review the correct behavior.
Regards,
Mama Meep
Player Behavior & Game Support
❄️ Meep Collector ❄️