Providers of systems generating synthetic audio, image, video, or text content must ensure outputs are marked in a machine readable format and detectable as artificially generated or manipulated, where the article requires it. The law also says the technical solution should be effective, interoperable, robust, and reliable as far as technically feasible, taking account of content type, implementation cost, and the state of the art.
This is a technical implementation problem as much as a legal one. Teams should define where the marking is created, how it survives downstream handling, and how QA verifies it.