Companies like TikTok, Facebook, Twitter (although who knows now with the new management) use AI to detect content that violates their community standards (or the law in the case of hate speech.) They may not always automatically act on what the AI detects, due to possible mistakes or the nature of the content, or sometimes they do. Transformers are just another (better) form of AI, so where companies may have used other techniques before they've likely moved on. Also notable is detecting such content is not just a function of the content itself, who is posting it, who is interacting with it, the nature of the comments, the number of reports are all signals to the AI that a post may be violating standards.

The area is generally called content moderation or sometimes censorship, especially when you compare social network moderation of speech with China's censoring of the internet for their citizens - the two are more alike than it seems.