>>329015831. Due to powerful government propaganda they actually think that Taiwan is owned by China and anyone that says otherwise is directly attacking China and Chinese people, so they get really mad over it. Brainwashing, basically.
2. Multiple Holos have done Taiwan "yabs" in the past, Cover apologized and said they would instruct their talents about the sovereignty of China over Taiwan so they don't make that mistake anymore (this was a lie and basically just PR, obviously. They probably just wrote an email that said "don't say Taiwan" that most of the girls didn't read)
3. Haachama did a Taiwan yab of her own the night before (while Coco was asleep) and her Bilibili channel got banned.
Because of those points, they interpreted Coco's Taiwan mention as a deliberate attack on Chinese people, as revenge for Haachama getting banned the night before, rather than a complete coincidence which it actually was. To make matters worse, Cover management forbid Coco from talking about it, so she was unable to explain herself until it was too late. They instead opted to appear to punish her in the hopes that the Chinamen would calm down, but that didn't work. The Chinese antis then used Coco's silence and lack of apology as proof that she deliberately tried to insult Chinese people, allowing them to build an army of angry spammers, including schizo nationalists from outside of the vtuber fandom.
Interestingly this also indirectly led to Rushia getting fired. After her Discord yab she was instructed to shut up and do nothing, but after seeing that strategy fail with her friend Coco she decided to try to clear her name on her own, which lead to management axing her.