it weaves an imperceptible watermark directly into the text itself. You won’t see it, and it doesn’t change the meaning, quality, or readability of Claude’s response

That's John Gruber quoting Anthropic. Gruber's completely correct on this one. Either there's non printable Unicode characters, or the word choice is biased, and the Anthropic statement is lies.

Does Anthropic really think they can claim magic and everyone will just accept it, or have they spent too long communing with Mr Flattery and can no longer distinguish reality from fantasy?