In my latest series of tweets [1] I tried to argue that this is not the case in a less technical way, not sure if I was successful though. For anyone not fluent in Korean, my argument was as follows:
Stable Diffusion was trained with a data set composed of about 2.32 billion text-image pairs. The model itself by comparison weighs about 4 GB. If the model somehow stored those images (completely disregarding texts) in the compressed form, it would be less than 2 bytes (EDITED) per each image. Whoever downloaded an image from the internet can see this is absurd. In reality 4 GB of data is the juice extracted from the data set, and if you could actually recover an original image from it then the juice must have had a recognizable residue, which would be pretty undesirable.