The actual rules don't say that I think, it's more about the intention that the watermark is embedded with the image/multimedia itself, so it's persisting even if someone "right-click > save" the image or takes a screenshot, not literally regulated the watermark has to be unremovable.

> (Summary) The icon should be directly embedded into the deep fake or published text (except for creative works), unless equivalent alternatives are available such as a user interface overlay. The icon must be visible when content is reshared or downloaded.