Tina: [Broken Access Control] letting any TinaCloud user authorize against any self-hosted site
@tinacms/auth's isAuthorized(req) decides authorization by validating the caller's bearer token against https://identity.tinajs.io/v2/apps/${req.query.clientID}/currentUser, where the clientID comes from the request and is never compared to the site's own configured TinaCloud app id. The function answers "is this token a verified user of whatever app the caller named?" instead of "is this token a verified user of THIS site?" Any TinaCloud user can create their own free app, get a valid token …