Mostly-furry imageboard e621 has banned explicit art of human and essentially human children:
Due to challenges stemming from changes in the political and legal environment, both offline and online, we have had to adjust our content guidelines to preserve access to our site. As a result, any content featuring young human or humanoid characters in explicit situations is now prohibited and will be deleted. This change also applies retroactively, and we have already removed all existing submissions featuring such content.
Administrator NotMeNotYou later clarified that "busineses partners" had demanded the change, which related to their ability to make money, and that on-site adverts were not the issue:
There is no single law we can point to as the tipping point, and while we were sitting pretty unaffected by most things, the same can't be said to a bunch of our business partners who did not appreciate the heat we attract. And since we can't function in a vacuum we have had to adjust.
Things change, they were okay with it previously and now they aren't. They want to continue making money and we're stuck with the consequences. And no we can't just stop business with them, there's no way in hell we would be able to cover the gap that would cause, be it donations or otherwise.
Guess what put pressure on some of our partners? That's right, governments.
Guess who would like to continue doing business in places where those governments are? That's right, our business partners.
romaniaglory said:
The last thing you ever wanted to admit was censoring your website to appease advertisers.
Nah, all our ads are handled directly by us and as far as I am aware none of them had any issue with the contents we host.