According to Flickr, “Photographers who craft and create work that might be considered risqué by some will have a safe place online to interact with one another, share mutual interests, and put their art into the world without the fear of it being removed or them being banned entirely from the communities they love.”
Flickr notes that in the past and on other platforms, the sharing of explicit/risque content can sometimes lead to the images being deleted or the photographer banned from the platform, so by putting it behind a paywall, it ensures that only those who want to see such images will be able to do so, and the creators behind them will be “safe” (as long as the images aren’t illegal, of course).
In addition to this change, Flickr has also announced that users who might not want to make their photos public will soon have to pay for that privilege. The company says that they will limit free account users to 50 non-public photos, so if you primarily use Flickr as a way to share your photos with friends or family members, you might need to upgrade your account if you plan to have more than 50 of these private images.