The parent company of TikTok is ByteDance which is a company based in China. But TikTok as a company isn't based in China.

From its Wiki:

Its parent company, Beijing-based ByteDance, is owned by founders and Chinese investors (20%), other global investors (60%), and employees (20%). TikTok Ltd owns four entities that are based respectively in the United States, Australia (which also runs the New Zealand business), United Kingdom (also owns subsidiaries in the European Union), and Singapore (owns operations in Southeast Asia and India).

TikTok says that since 2020, the US based CEO is responsible for making important decisions. However, multiple reports claim that there is little functional separation between TikTok and its Beijing-based executives and software developers. TikTok has been noted for downplaying its connection with ByteDance and for eschewing questions about its relationship with the Chinese government.