Facebook API Publishing Requirements and Breaks
Publishing to Facebook through the API needs four things: a Facebook Page, a person who can perform the CREATE_CONTENT task on that Page, an app holding pages_manage_posts with the two permissions it depends on, and a Page access token issued through that person. Personal profiles are not a destination. Serving Pages for people outside your own app team adds a fifth requirement, Advanced Access, which means Meta App Review for each permission and a verified business. After setup the connection still depends on that person: when they lose access to the Page or their token is invalidated, publishing stops.