Unfortunately Facebook/Instagram doesn't make it entirely clear how they track location data of their user and don't have geographical data for all users.
Unknown locations can be due to many reasons. Users may be using a VPN to mask their location, haven't allowed Facebook or Instagram access to their location settings, have location settings switched off on their devices, to name a few.
Instagram choose not to display unknown locations within their own in-app insights so when comparing this to Kitly data you may see some slight differences. Instagram assumes the location of some of their users whereas Kitly provides you with an accurate number of those that have disclosed their locations.
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