ohh, turns out a negative "ipv4.dns-priority" value on the VPN connections makes all other connections lose their DNS settings. So now I have it set to 0 for the VPN as I don't care about DNS leaks, or rather I prefer if all non redhat.com DNS requests go through my local DNS server 🙃
I might have to play around with the priorities a bit more, but finally that's figured out :)