Look up Elsagate. Nobody knows what started it, but foreign channels invaded the site and started creating bizarre videos that borderline on being pornographic, yet they were marketed to children. YouTube's response? Remove comments on videos marked for kids.

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Wasn't that the response to them illegally gathering and collecting data on users under the age of 13?

Not that either. It was due to a video by Matt Watson about people perving in the comments on videos with kids in it. He later took down his YouTube channel shortly after making the video.

If you have time to kill, here are some videos by EmpLemon about it.

Part 1 https://www.youtube.com/watch?v=nBQFls_elpY

Part 2 https://www.youtube.com/watch?v=XIYyQEbLtHc