The watermark is in the text. If you copy the text you're copying the watermark which is part of the text.
Computerphile on YT has a video explaining how models can fingerprint the text they produce. Essentially they modify the probabilities of word choice slightly in a predictable way.
Computerphile on YT has a video explaining how models can fingerprint the text they produce. Essentially they modify the probabilities of word choice slightly in a predictable way.