Context: https://en.wikipedia.org/wiki/Self-censorship
Self-censorship is the act of censoring or classifying one’s own discourse, typically out of fear or deference to the perceived preferences, sensibilities, or infallibility of others, and often without overt external pressure.
In addition to the articles on censorship, remember that the can media preemptively bias their content by only hiring those who demonstrate a shared point of view. This is done before any need for actively censoring jouirnalists – just hire the faithful rather than objective investigators.