Most likely some sort of fingerprinting of your device.. Since you use three different facebook services as well providing the access to phone number of the de

Most likely some sort of fingerprinting of your device.. Since you use three different facebook services as well providing the access to phone number of the device to whatsapp, facebook has a pretty solid idea who the device belongs to. This is an opinion not a fact but is something that is extensivly used to identify returning users (on i.e. different browsers / devices etc.) To services