You cannot block Facebook directly in Tik Tok, however, you can limit it by following the Tik Tok privacy settings and hiding the unwanted content and reporting the Facebook-related advertisements and accounts that you do not want to see.
If you’re wondering how to block Facebook on TikTok, the app can’t block platforms directly, but you can reduce Facebook-related content. Open a video about Facebook, tap “Not interested”, and hide similar posts. You can also filter keywords and adjust content preferences in Settings → Content preferences.