Permaban ?

Hello, this is probably my first post on the forum so sorry for that, today, I was permanently banned on EUW after getting back to the game, I dont believe I have done anything toxic at all (I have a clean record, 0 bans before. ), and I did not receive any chat logs or motif in my e-mail ban. I have been banned until the Mon Feb 23 06:22:22 UTC 2105, does anyone knows what it means ? Someone was threatening to report me because i was "smurfing" (Which I was not, I just got back to the game after three years ), could it be the reason to my ban ? Is there any way to know exactly why I got banned :/ ? Sorry if the post feels stupid, just genuinely asking if anyone knows, thank you.