In my understanding this law in question requires US-based app stores and ISPs to stop hosting for Bytedance. Assuming they comply with this fully, your packets can still reach arbitrary address in China due to the technical nature of the Internet. US would have to examine every outgoing packet and block a lot of organizations' IPs around the world (e.g. a Brazillian CDN that has no presence in the US) to make Tiktok inaccessible.
It's very much a technical problem is the point I was making. Significant portion of Chinese users bypass the ban to access American services. There is a wide spectrum of possible GFW implementations the US can choose from. Anything short of the North Korean one, Tiktok is not going to be completely banned.
Case in point: I saw another commenter managed to access Tiktok by remotely operating a Windows server located in Canada, should their ISP / cloud provider they rented server from / Tiktok Canada be held liable for serving this user? What about users who simply alter their DNS / use socks proxy / VPNs to gain access? The US could develop technology to ban all this, then it would end up exactly the same as China.
It's only partially a technical problem -- most of the issue lies in the rubber hose.