Where does it say that? It says they could do that, not that they are doing it.
Although nothing indicates that Facebook currently collects user messages without manual intervention by the recipient, it's worth pointing out that there is no technical reason it could not do so. [...] An "end-to-end" encrypted messaging platform could choose to, for example, perform automated AI-based content scanning of all messages on a device, then forward automatically flagged messages to the platform's cloud for further action.
Although nothing indicates that Facebook currently collects user messages without manual intervention by the recipient, it's worth pointing out that there is no technical reason it could not do so. [...] An "end-to-end" encrypted messaging platform could choose to, for example, perform automated AI-based content scanning of all messages on a device, then forward automatically flagged messages to the platform's cloud for further action.