There are multiple ways of doing this and I’m not sure which methods tik tok is using.

• ip address there’s a group called IANA that issues blocks of IP addresses to ISPs and there a companies like Maxmind that package that info. apps can create rules block requests based on that info that block requests coming from a specific location or return an error to the user

• removing from the app store Companies can ask app stores to no longer offer downloads in a specific region and as the app updates it will become more busted over time

• user information Based info provided by the user directly during sign up or from the social login a user used to sign up with tik tok