I set up NextDNS on my phone (Pixel 3 running GrapheneOS) and checking the logs from my account. I see DNS queries from my VPN IP address, but also some queries to gstatic.com from my real home IP address. Does this mean that my always-on VPN on GrapheneOS has been actually leaking my real IP to Google? I find that extremely disturbing.
Android sends a query to gstatic.com to get the IP of the DoT server, and this request does not use VPN to connect
So yes, google knows you’re using nextdns but that’s all they know
If you find it disturbing you can just block the domain and from what I’ve tested it doesn’t cause problems