I don’t know the details of this app’s corporate structure, but if it’s developed here and user data stays here it would not qualify under the act. Based on the context of your and other comments I assumed it was also a foreign-controlled app

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?