"First of all, the Chinese are so nice, they're so sweet and so welcoming. They've over here teaching us Mandarin."

Millions are joining RedNote ahead of the TikTok ban. But the app’s default language is Mandarin. “Oh so NOW you’re learning mandarin,” Duolingo tweeted on Monday.

The threat of TikTok going dark in the US appears to have compelled some Americans to start learning Mandarin as they look to communicate on a rival Chinese app. Many Americans are joining RedNote, also known as Xiaohongshu,