In the early stuffs, Stable Diffusion 1 (not XL 1!) and such, if you prompted for stock photo style images, you regularly (~30%) got something resembling the Getty stock photo watermark in the lower right.
Was quite annoying but adding "public domain, Creative Commons" to the prompt usually got rid of it (the model knows that public domain images have no watermark :-). Since SD2.0 I haven't seen this happening at all.
I've generated thousands of images using SD 1.5 based models and I've never got the getty watermark. That makes my think that some dishonest lawyer used img2img.
Was quite annoying but adding "public domain, Creative Commons" to the prompt usually got rid of it (the model knows that public domain images have no watermark :-). Since SD2.0 I haven't seen this happening at all.