Ah ok, it actually was a module - in my case TM Mega Menu.
I just edited the file modules > tmmegamenu > tmmegamenu.php
Somewhere there (line ~2679) are two lines like this
'://maps.google.com/maps/api/js?region='.Tools::substr($defaultcountry->isocode, 0, 2);
I just removed the first part so it looks like this:
:''.Tools::substr($defaultcountry->isocode, 0, 2);