DNS juggling between Systemd and Linux VPN app

Questions
1

I am using NextDNS via systemd-resolved as suggested by NextDNS setup.

I tried using ProtonVPN and Windscribe. Both are using systemd DNS instead of their own. It’s super hardcoded in resolv.conf. I tried removing all stuck to on IPv4 DNS server with DoT. But now system resolved DNS with both nextDNS and VPN DNS.

I was thinking of using NextDNS when not using VPN and VPN with its own DNS. It’s getting headache. I can’t use split tunneling properly due to these leaks. Any Ideas ?

I think it’s a nightmare for certain people who has my setup alike. Leaking DNS without knowing.

2

If you use Windscribe, you can set the upstream DNS as NextDNS in their app

3

I want VPN app to use its own DNS when using it not System DNS. That is the main leak, I am discussing here.