Hints on setting up Pi-Hole as a local DNS Server

What's the reasoning behind picking v5-0 and ftldns-beta as categories for your topic?
Pi-hole 5.0 has been released in May 2020 - there is currently no beta test.

With regards to your observation:
It would seem you are referring to DNS resolution for the machine that hosts Pi-hole, and since you are talking about updates, it may be a good idea to read the release notes:

  • Pi-hole no longer changes the nameserver assigned to the Pi (in /etc/resolv.conf). The existing nameserver settings for the Pi-hole host are respected and unchanged.

Also, have a look at Correct Resolv.conf entry in pihole 5.11 - #2 by jfb for different valid choices for your personal pick of DNS servers for the Pi-hole machine itself.