https://www.cnet.com/news/tumblr-will-be-porn-free-starting-dec-17/

Tumblr will allow nudity in some scenarios though. Breastfeeding and nudity in art are still okay to post.

The service, which hosts about 450 million blogs, will start sending out emails to users whose content have been flagged as adult. Once flagged, the post will be set as private and only be viewable to the poster.