Have you read this article yet? You may want to start here. Like traditional broadcasters, social media platforms choose—through their algorithms—which stories to amplify and which to suppress.
https://themarkup.org/citizen-browser/2021/01/05/how-we-built-a-facebook-inspector
https://themarkup.org/citizen-browser/2021/01/05/how-we-built-a-facebook-inspector