The streamer misspoke and viewers flooded the chat.
Tips
culture
弹幕 ('bullet curtain') are comments that fly across the video screen, pioneered by Japan's Niconico and adopted by Bilibili. 刷 (to scrub / to grind) indicates repetitive, high-volume posting.
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Bilibili / Douyin / live-stream vocabulary. 刷屏 is a close cousin (to flood a chat screen in general).
