For example, YouTube does this with some LGBT content. YouTube has demonitized LGBT content and placed it in restricted mode, which screens for "potentially mature" content[1][2].
YouTube also shadowbans the content[1], preventing it from showing up in search results at all.
From here[1]:
> Filmmaker Sal Bardo started noticing something strange: the views for his short film Sam, which tells the story of a transgender child, had started dipping. Confused, he looked at the other videos on his channel. All but one of them had been placed in restricted mode — an optional mode that screens “potentially mature” content — without YouTube informing him. In July of that year, most of them were also demonetized. One of the videos that had been restricted was a trailer for one of his short films; another was an It Gets Better video aimed at LGBTQ youth. Sam had been shadow-banned, meaning that users couldn’t search for it on YouTube. None of the videos were sexually explicit or profane.
There are more examples like that here[2].
[1] https://www.rollingstone.com/culture/culture-features/lgbtq-...
[2] https://www.washingtonpost.com/technology/2019/08/14/youtube...