What is used to generate it?
Been stated a few times in the thread.
What's heavily used is Unstable Diffusion to run it on your own desktop or you can use Google Colab if you don't have a desktop with a graphics gaming card.
You use what's called a Checkpoint model from sites like CivitAI.com to create different styles of output.
Then there's sites that allow you to input prompts to generate images like PornPen.ai also some on Discord as well.
Other stuff that don't do adult pics is Leonardo or Midjourney which there's other threads on here that will give you AI outputs from what you tell it to do.