https://www.theguardian.com/media/2018/jul/26/what-is-shadow-banning-conservatives-twitter-trump

Conservatives believe they’ve found proof of anti-rightwing bias in social media. Twitter says they haven’t. An explainer

“Twitter ‘SHADOW BANNING’ prominent Republicans,” Donald Trump tweeted Thursday morning. “Not good. We will look into this discriminatory and illegal practice at once! Many complaints.”