This is a national security threat. If any of my followers were mad about Russian election interference exploiting social media platforms, you ain't seen nothing yet — the 4d chess move is to own the social network.
When opening a website from within the TikTok iOS app, they inject code that can observe every keyboard input (which may include credit card details, passwords or other sensitive information)
TikTok also has code to observe all taps, like clicking on any buttons or links.