Tiktok account not working in the US

My boyfriend came to visit me in the US and it's so weird his account doesn't work in the US, but if I log with mine it works.

He can only use tiktok with the Tiktok Lite app. Otherwise his profile doesn't load neither he can't watch any videos. Does someone know how to fix this?

We have tried, clean cache, reinstall the app, but seems not to work.