No, the law doesn't give a users threshold: it names ByteDance and TikTok specifically, and provides a mechanism for the President to add new companies controlled by a "foreign adversary country" to the list. So anything at all by ByteDance is banned, but RedNote is owned by a different company that would have to be targeted separately under this law.
https://www.congress.gov/118/bills/hr7521/BILLS-118hr7521rfs...