European authorities are threatening TikTok with hefty fines and possibly forcing the suspension of some aspects of a new spinoff app that was released last month, which regulators claim has addictive elements, this week.

TikTok Lite, a less data-intensive version of TikTok’s main app, is the subject of the warnings. It has a feature that pays users money for using TikTok content and app features.

EU officials have expressed concern that TikTok Lite users may become addicted to the app due to this feature, calling it an “experiment” on gullible EU nationals in Spain and France, where TikTok Lite has been made available.

The European Union’s decision on Monday represents the trading bloc’s second significant investigation into TikTok. It focuses mostly on TikTok Lite and the potential for considerable negative effects on users’ mental health, according to authorities.

The action was taken a few days after the US House of Representatives approved legislation that, due to national security concerns, may eventually forbid TikTok from operating within US borders.