The core or the underlying needs of the product are different. If you have used Chinese social products, the menu bar is on the right. That's based on the habits of its 1.3 billion users, because TikTok was born in China. Now the experience is optimized enough to go global.
Discussion
Haven’t used the Chinese version but I imagine different cultures do things a bit differently. I know for example in Japan, information density is favored over white space.
Agreed. Japanese architecture and style are the same. But it doesn't seem like there's much difference between the UI on TikTok in Japan and the US.