"Because of something she said on stream", the only thing that could mean just a couple months after debut is the trap thing. "People love her or hate her", not 'are upset about her saying a word', but 'hate her'. They've gone beyond being upset at a word and became antis.
Using the oshi mark is place of a persons name is a common tactic when you're trying to not show up on their searches (I'm pretty sure several vtubers have said that it doesn't work at all and they still see everything, so at that point all you're doing is tipping your hand).
Put it all together; neah and his friends were hate-tweeting to each other and people posted screenshots of it, so he complained "just leave me and my petty hate groups alone so we can hate-post in peace", because he didn't want to be called out over it.
TL;DR, it was about the word 'traps' for roughly 2 seconds, but that was nothing more than a trigger that lead to him and his friends just hating in general:
Unless you believe his public insinuation here that he didn't
participate in the petty hating, he just
read it. But I'm willing to bet he's much more of a twat in private than he is publicly, and even his public persona is not good.