Sure they are. However, all dns servers are going to have this issue. Even most selfhosted ones, like a self hosted pihole use Google DNS as its backend.
The data is far less valuable than your original claim of "Why would someone route their traffic through your servers" which sounds like a VPN/Proxy.
The data is far less valuable than your original claim of "Why would someone route their traffic through your servers" which sounds like a VPN/Proxy.