Here is some insight in to how Twitter’s shadow banning algorithm’s may be operating.
In addition to their “machine learning” (a good but significantly over-hyped technology) scanning of messages, their algorithms take in to account user reports, and the muting or blocking of accounts to decide if individual tweets or accounts should be shadow banned. The user that is shadow banned is not notified of the ban.
Once shadow banned, one’s Tweets may not show up in some follower’s Twitter feeds, may be excluded from search results, and generally made invisible. In the former, a shadow banned tweet (or account) might have Tweets appear only in news feeds of existing followers – thereby seeming to continue to have normal interactions so that you are not aware of the shadow ban. However, as I discovered for a 4 week period when I posted screen snap shots of HealthCare.gov actual price quotes – I gained zero new followers, although my existing followers continued to interact on the topic. The lack of new followers is a sign that my account likely had a partial shadow ban. I previously gained my largest influx of new followers when I had posted similar Tweets earlier in the year, giving more evidence that my account was partially shadow banned by Twitter because a Twitter employee did not want this public information to be disseminated.
Shadow bans are not necessarily permanent and in fact, may generally be temporary.
Update: Another way that Twitter controls the tweets you see is that Twitter curates your news feed. Twitter selects the content that Twitter believes you want to see and highlights those Tweets at top. Twitter also selects content from other people to display your news feed – content from people you do not follow.
The combination of curation, insertion of random tweets from people you do not follow, down ranking and shadow banning means that Twitter is George Orwell’s 1984, in real life, directly controlling the information you see. Twitter is basically a massive propaganda operation. If Twitter were based in Russia, North Korea or Iran, the U.S. would be loudly proclaiming Twitter as a tool of an evil regime.