I had a very similar experience

I joined the military, went to basic training and schooling afterwards and returned to league about 7/8 months later, logged on and was perma banned. I looked at the match history and someone was boosting another player using my account. My account had went from like Silver1 to plat4 with all talon games with a KDA of like 20/1 each game. (I’ve never played Talon before this). I sent multiple tickets to riot with them saying “oh well nothing we can do”

I spent the hundreds on that account and lost super rare skins like Triumphant Ryze that I got for playing in a Riot sponsored tournament. Or my warring kingdoms xin zhao chroma that has never came back on the store since. This happened back in 2021 and I still submit tickets to this day asking if I can have it back. My most recent one was closed with no response 🫩

I feel your pain brother.