For anyone that needs this (copy pasted from a comment 2 weeks ago)

Your DNS can also do things like block malware, adult content, trackers, social media, or other things. Here's info about cloudflare and mullvad.

  # Cloudflare
  ## Standard
  1.1.1.1
  1.0.0.1
  2606:4700:4700::1111
  2606:4700:4700::1001

  ## Block Malware
  1.1.1.2
  1.0.0.2
  2606:4700:4700::1112
  2606:4700:4700::1002

  ## Block Malware & Adult Content (not useful for this case)
  1.1.1.3
  1.0.0.3
  2606:4700:4700::1113
  2606:4700:4700::1003

You can find cloudflare information here[0], and remember to make sure you setup DNS over DoT (TLS) or DoH (HTTPS). Especially for them they will want to have encrypted DNS.

Mullvad also offers free DNS[1], which also supports encrypted DNS

  # Mullvad
  ## DoH is port 443 and DoT is port 853
  ## Standard
  dns.mullvad.net
  194.242.2.2
  2a07:e340::2

  ## Block Trackers
  adblock.dns.mullvad.net
  194.242.2.3
  2a07:e340::3

  ## Block Trackers + Malware
  base.dns.mullvad.net
  194.242.2.4
  2a07:e340::4

Mullvad also has block for Adult + gambling and social media (so there are 6 total configurations). You don't need the Mullvad VPN to use these.

I should also mention, as this frustrated me a bit, that your browser may implement its own DNS and so just setting these in your router (or pihole) may not completely resolve the issue. In Firefox, go to Settings > Privacy & Security > (scroll all the way down) Enable DNS over HTTPS using > then under either "Increased Protection" or "Max Protection" you can set a DNS resolver (or turn it off). They have defaults for Cloudflare (default!) and NextDNS. While you're there, also check your settings at the top of that page about "Enhanced Tracking Protection"

I am NOT a network/security person and would greatly appreciate replies to this comment with additional information. Especially about setting up things like piholes, TVs, browsers, encrypted DNS (especially this!), host files, and so on.

[0] - https://developers.cloudflare.com/1.1.1.1/ip-addresses/ - https://developers.cloudflare.com/1.1.1.1/setup/#dns-over-ht...

[1] https://mullvad.net/en/help/dns-over-https-and-dns-over-tls