But you do agree enabling network location provider does break the anonymity that the owner VPN would offer? You also do agree your average user cannot possibly realize this would happen, as it requires deep understanding of how VPNs and network location queries work?
It does not break the anonymity of the VPN. When using the recommended proxy mode, it sends location data (nearby Wi-Fi networks and also cell towers when we add it) through an HTTPS connection with pinned TLS keys (Let's Encrypt roots and our backup leaf keys) to a GrapheneOS server which then sends them to Apple. That's why it's not enabled by default. This does not break the anonymity of a VPN. Your claim would also apply to using online maps app to search for a route from your house to somewhere else or giving location data to any other service. We're very clear about how network location works and it's not enabled by default so there is no need for concern about this. It will also support offline usage which is being actively developed.
Cannot you just add a short warning to the option enabling network location provider, like, "It is recommended to leave this off if you use VPNs for anonymity". It is a small change, and absolutely enough to discourage people with serious threat scenarios from enabling it, while not discouraging anyone else from doing it. Very easy to understand, it is a clear and concise warning.
We're clear that it sends location revealing data to a service. It's similar to sending location data to other services such as using Google Maps, Tinder, etc. although most people would trust sending that to a GrapheneOS service with a reasonable TLS key pinning setup much more than sending it elsewhere. That's there in the explanation.