In their case it wasn't a local VPN.

True, I somehow though we were talking about the digital wellbeing apps that Apple copied and banned.

How can a VPN be local? If there is no vpn server at the other end is it really a VPN?

The phone itself is the VPN Server. Its a trick used for the app to look at some of the network traffic.

Cloudflare's 1.1.1.1 app does the same thing but for DNS, to capture the DNS requests from the phone you need to create a "local vpn", but not all your traffic is going though Cloudflare (yet, they do plan to add a VPN to the 1.1.1.1 app at some point).

EDIT: All Custom DNS settings apps for mobile connections on iPhone (I forget if Android is the same) ate like this. I use nextdns and their app does the same.

Thanks for the explanation

The VPN is local if both the client and the server are local.