That don't abide by Chinese law. There's a reason Bing and Skype are still allowed in China. The US government has no proof of TikTok or WeChat violating any US laws that other American companies haven't.
All companies in China are required to do whatever the CCP tells them to do.
If you have more than 100 employees, you must have a member of the CCP to provide oversight.
Zhang Zhiming, the CEO of Byte Dance publicly grovels to the CCP. Here is his public statement:
https://www.youtube.com/watch?v=BZa0FGThXak&t=5m4s