After how many chat restrictions you start to get banned?

I remember there's like a 7 days ban, then more and more, then perma ban that eventually can be lifted if you act like a saint or something. Is there an official documentation from Riot on this? I'm at 25 games restriction and I was wondering how many other times I can do that before getting banned, and if I start getting temporary bans, then how many, etc etc Thanks
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