Got banned

So recently my account was permabanned but I'm not sure why. I didn't receive any email as to why I was banned and my account has never had any kind of punishment (chat ban, two week ban etc.). What I think may have caused the ban is that I was being toxic in a couple of recent games I was playing with my friends. However, I did not use any kind of racial slurs, homophobic remarks or anything else of that kind of nature. it was more your generic run of the mill "bro you suck why are you dying so much" type stuff. To my knowledge toxicity does not call for a intsta permaban unless it is especially crude. Unless what I said in the example I said before is considered especially heinous (which in my honest opinion I dont think it is BUT it is still toxic). I'm not asking for any kind of validation or trying to justify anything I'm just curious if anyone else has experienced this under these circumstances as well and if they might be able to give me an explanation. I have already sent a support ticket and am just waiting for a response from riot themselves. Also, I would like to add that I was/am not using any third party software or anything of that nature. Thanks!

UPDATE: So I got my account back. It was a security suspension like someone said since a charge on my card was chargedback for some reason. Just had to balance the fee and I was all set. Thanks for your input guys!