TikTok collected identifying data that allows the app to track users’ online activity from millions of devices, according to a Wall Street Journal report. The app dodged a privacy feature in Google’s Android operating system to gather the information, using a tactic that violates Google’s policy limiting the ways that apps can collect user data. TikTok stopped the practice in November, according to the report. The revelations come as President Trump mulls a ban on the popular video app in the U.S. over concerns that its Chinese parent company, ByteDance, could use data collected from users to aid the Chinese government in tracking U.S. government officials. TikTok insists that it does not give user data to the Chinese government.