Any example of chat logs? Everyone has different standards of what's toxic and getting offended. I'm personally very easily offended, so basically I spot out some languages that may trigger other players.
On the hand, you are certainly not the only one getting punished. I see quite some people share their stories of punishment. Riot doesn't give enough feedback about your report being successful, and free accounts are very accessible so the default MMR (bronze 2 to silver 3) are usually plagued by repeatedly punished players. I couldn't think of a good solution to it. (Although chat restrictions may work better than the previous banning system).