Thanks to the One Child policy and all of its implications, there's an estimated 25 to 30 million more men of marriagable age than there are women. That's men who, mathematically, will never have a wife unless they leave the country. That's about 8% of the entire population of the USA in unmarriable men. China has an enormous incel problem, and it's largely the CCP's doing. A perfect audience for a small number of cute anime girls soliciting donations.
With such a large base of thirsty men, it's no surprise that the population of vtubers expanded so quickly there. Unfortunately, being popular in China has its drawbacks. Incels are jealous by nature, so having a large number of them as an audience is just asking for trouble down the line. It's like having thousands of jealous stalker ex-boyfriends, except (thankfully) most of them are stuck in another country, most of them don't speak your language, and they don't know your address even if they could leave, but (unthankfully) they can still harass and dox you online until they finally get bored and move on. Sprinkle in some extreme enforced nationalism and the problems become inevitable, since China's policy of political kowtowing is universally reviled by everyone outside the CCP's grasp.
That said, it's estimated that the one child policy averted at least 600 million births (including second-gen births, the children of those born under the policy). An extra half-billion Chinese is an unpleasant alternative to think about no matter which side of the border you're on. Maybe we should be thanking these people for taking the government-approved incel bullet.
They've been trying to post dox on Twitter and getting banned about as fast as you'd expect. I've seen the gif of Fubuki's roommate more times than I can count, but it's usually buried within minutes. I haven't seen it recently, though, so maybe they finally gave up on that route.