An analysis published by the American Wall Street Journal showed that TikTok tracks user data secretly using a method that Google has banned.
The analysis found that the application avoided protecting privacy in the Android operating system from Google, in order to collect unique identifiers from millions of mobile devices, information that allows the application to track users' data over the Internet, without allowing them to cancel the subscription.
This method, which mobile security experts said was "concealed by an extraordinary layer of encryption," appears to violate Google's policies that limit how apps track people, and has not been disclosed to TikTok users.
The newspaper's test showed that TikTok stopped this feature in November last year, after 18 months of continuous use, in clear violation of the rules of the Android platform, which the newspaper attributed to the increasing political pressure from Washington.
The addresses could act as a unique identifier for each user's device, making them valuable for both ads, and possibly the most invasive forms of tracking.
By 2015, the Apple App Store and Google Play Store banned the collection of MAC addresses as a matter of policy, but TikTok was able to obtain the identifier through a vulnerability.
A study cited by the newspaper found that nearly 350 apps within the Google Play Store had taken advantage of the vulnerability for ad targeting purposes.
The results come at a time when ByteDance - the parent company of TikTok and based in China - is under pressure from the White House over concerns that the data collected by the app could be used to help the Chinese government track down US government employees.
Tik Tok said he does not share the data with the Chinese government, and will not do so if requested to do so.
The identifiers collected by TikTok, called MAC addresses, are commonly used for advertising purposes.
The White House said it was concerned that the Chinese government could obtain user data and use it to build detailed files on individuals for extortion or espionage.
The Chinese video app said earlier this year that it collects less personal data than US companies, such as Facebook and Google.
A company spokesman said in a statement, "We are committed to protecting the privacy and security of the TikTok community, and we constantly update our application to keep pace with evolving security challenges. The current version of the application does not collect MAC addresses, and we encourage our users to always download the latest version of TikTok."