The tracking endpoint now accepts optional country and city fields. If your app already knows where a user is from its own profile data, that's usually more reliable than a lookup based on their connection, which VPNs and carrier networks can skew.
Values you send take precedence. If you leave them out or send an empty string, location detection fills them in as before, and if neither is available the stored value is left alone. A client's IP address is still derived server-side and is never accepted from the caller.
Available now for all API users. Nothing changes unless you start sending the fields.