like 4 months ago a Streamer was banned for buying almost 300.000 Gold on third-party site and he got banned for 2 years (last update he has) - the support told him it is not allowed to create another account while this 2 years of ban still exist. But now, he created 1 month ago a new account, bought a lot of gold and still streaming lost ark on twitch.
On the other site i know different people, getting banned for literally nothing and being still banned with other accounts they created afterwards.
Report it. All you can do. CMs won’t comment on game bans like this, nor do they have the ability to look up that info. While it may officially be against the TOS to create a new account while suspended there is nothing to prevent people from doing this. As a result, it is VERY common to see people doing this. Especially people that are whaling hard.
I mean you might be able to get him banned or, at the very least removed from the partner program on twitch assuming he is partnered. Though you would need to prove that he is actually cheating. But like @irvine774 said, its really not worth losing any sleep over.