While the filters have been around since August 2016 and were supercharged in May, Twitter's aggressive censorship of conservative accounts was noticed Thursday afternoon by the Daily Wire's Ryan Saavedra, after he said he saw reduced activity following a viral tweet with 3.85 million views in which Democratic Rep. Maxine Waters (CA) calls for attacks on members of the Trump administration. In short order, a flood of influential conservative Twitter users discovered they were shadowbanned also using an account checking tool at shadowban.eu.

Twitter VP of Trust & Safety, Del Harvey, said that the filtering algorithm look at a number of signals, including how often a user is blocked, muted or complained about vs. receiving positive interactions such as "favorites" and retweets.

"If you send the same message to four people, and two of them blocked you, and one reported you, we could assume without ever seeing what the content of the message was, that was generally a negative interaction."