Social media DNS Blocklists for Pihole/AdGuard.

1. Login into Pi-hole admin
2. Navigate to Settings
3. Expand Pi-Hole's Block Lists
4. Copy this URL: https://raw.githubusercontent.com/gieljnssns/Block_facebook_dns/master/pihole-facebook.txt
5. Paste the URL in the Edit box and click on Save and update

1. Login into AdGuard
2. Navigate to Filters
3. Click Add filter
4. Enter name
5. Copy this URL: https://github.com/gieljnssns/Block_facebook_dns/raw/master/adguard-facebook.txt
6. Paste the URL in the Edit box and click on Add filter

https://kb.adguard.com/en/general/how-to-create-your-own-ad-filters#example-blocking-by-domain-name

You're done.