(Honest question) How does getting banned for being boosted work?

PSA: You are at risk of being banned for MMR boosting even if you've never done it. Here's proof.
Please read through the post before immediately assuming this is just some shitty booster crying about a ban. It's not. Yesterday, after a Normal game with a friend, I received a pop-up message saying my account was banned and that the client was going to exit.
So I am a person who hasn't played much ranked over my years of playing league. recently I have gotten into playing ranked. (obviously since its pre season it does nothing) My friend recently has been banned for being boosted according to him wrongfully. So I did a bit of searching and i found this post. And now I am a bit concerned on how getting banned for being boosted works. Because i was on a 74% win rate from bronze 4 to 1 , and I have recently been on quite an annoying losing streak. Am I at risk of getting banned, and if so how could i safeguard my account?
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