Comment by zowie_vd

The LAION-5B dataset is public, so you can check directly whether a picture is in there or not. StabilityAI only takes a very limited amount of information from each individual picture, so for Stable Diffusion to closely reproduce a picture it would need to appear quite frequently in the dataset. There are examples of this, such as old famous paintings, "bloodborne box art" and probably many others, though I haven't looked deeply into it.