And I think it may be something to do with the refference image. It may had watermark looking blob on the bottom, so the system have been recreating it. Brainfog.... Thank you for checking.
@Jan33837015o56b are you using a reference image with a URL or other text at the bottom of the original? I've seen this when that is present on the original source.
Which models are you seeing a watermark from? Can you show us an example? I think some had watermarks in beta, but I just tested all the models and no longer see any watermarks on the models in text to image.