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China announces plan to label all AI-generated content with watermarks and metadata.
(english.news.cn)
This is a most excellent place for technology news and articles.
You can use things like steganography to embed data into the AI output.
Imagine a text has certain letters in certain places which can give you a probability rating that it's AI generated, or errant pixels of certain colors.
Printers already do something like this, printing imperceptible dots on pages.