The VPN doesnt leak my ISP dns. But yes I do have block all connections without VPN enabled.
The DNS leaks through when I set settings in the “static” internet settings on the main profile.
My setup is a wireguard VPN on my personal network, which utilizes locally hosted adguard and pihole servers. I check for leaks at https://www.dnscheck.tools
It’s more that abnormal traffic gets flagged, and you end up getting limited