The REDnot is not a "foreign-controlled" app, it's a foreign app, and it does not target the US market. The US citizens chose to use a non-US app. How would US enforce a ban? Send marines to Shanghai and capture CEOs?
REDnote is explicitly "小红书国际版", or "Little Red Book International Version" and is in English in US app stores. It's definitely targeting non-Chinese users.
Oh I misread your comment (read /inside/ rather than /outside/ for some reason), but obviously the same way they’re going to ban tiktok? Make it illegal for the app stores to host.
