TikTok and WeChat will both be banned in the US from Sunday, unless President Trump agrees to a last-minute deal. The ban is likely to take the form of an order barring US citizens from downloading messaging app WeChat or video-sharing app TikTok, and banning the apps from being distributed through any app store on any platform. It is assumed that access to them will also be blocked.
The reason for the ban is that the US government is concerned about the data of US citizens being accessed and processed by the Chinese government, which the US government considers a threat to its national security.
Microsoft had been expected to buy out the US arm of TikTok in order to save it, but recent negotiations between Microsoft and ByteDance (owners of TikTok) collapsed. Oracle is now in last ditch negotiations with ByteDance to buy the US arm of the platform.
The deal will need approval at the highest levels of the US government. Extraordinarily, Trump has said he expects the US Treasury to benefit financially from the deal if it goes ahead. This is mainly in recognition of the fact the political pressure exerted by the US government on the company has brought about the necessity for the fire sale and has driven down the price.
The [US Department of Commerce] acknowledged that the threats posed by WeChat and TikTok were not identical but said that each collected "vast swathes of data from users, including network activity, location data, and browsing and search histories". ByteDance has denied that it holds any user data in China, saying it is stored in the US and in Singapore. Tencent, which owns WeChat, has said that messages on its app are private.