Inside tailscale admin panel, under DNS settings you can specify which DNS server to use. I think by default that option is off.
I got my ON and pointing to 192.168.178.136 which is pihole. This options forces every device in tailsnet hit Pihole for DNS .
I have 3x n100 16gb ram as proxmox cluster. Have bunch of VMs, containers going. So far, 3 months in and not one single issue. And all 3 going at full tilt still uses less power then my previous single server setup. One of these n100s even have 3x proxmox virtualized where I tinker with cluster, ha, ceph, zfs and other stuff ... Like sandbox, before I move to live.