I constantly get these warnings on my linux computers and the /etc/resolv.conf keeps getting written to:
# resolv.conf(5) file generated by tailscale
# For more info, see https://tailscale.com/s/resolvconf-overwrite
# DO NOT EDIT THIS FILE BY HAND -- CHANGES WILL BE OVERWRITTEN
nameserver 100.100.100.100
search tail9f***.ts.net lan
I use pihole on a raspberry pi as my DNS server and my DHCP server.