How is TikTok able to screen this en masse? Are they going after tags? Political issues aside, I am really interested in the technical background in this.
Every large social network has fairly advanced mass screening setups for advertiser-sensitive topics. They just need to change the configs. On YouTube for example they will transcribe audio and run OCR on text to flag sensitive topics using MLP in order to flag certain topics (ex: Palestine/Israel), and prevent most ads from being shown (and demonetize and down rank).
Basically every large advertiser requires this so it's pretty trivial to turn on.
The only thing I could come up with, assuming this isn’t a technical glitch, is that TikTok already had the infra to silence anything they want on the platform and as soon as the keys were handed over they turned that filter up to 100%