The Media Devices query might always return "unique" on some browsers (e.g. Firefox). Firefox, for example, returns a random string which persists for that orig

The Media Devices query might always return "unique" on some browsers (e.g. Firefox). Firefox, for example, returns a random string which persists for that origin across a single browsing session (but which is different after the browser is restarted, for example). It's therefore like a cookie, but weaker in that it gets cleared on browser restart (and, in private browsing, it's always changing). So it's not very useful for tracking, since a site could just use a cookie instead. If that's your only Unique attribute, then your browser might be less unique than the website claims.