It could be that you haven't added the domain they're served from onto your blacklist.
A weird side story: I had a situation where an app on my Roku TV would crash if it failed to serve an add from a blocked domain (there were several but they mostly pointed to google ad domains). I actually _had_ to allow ads from the domains they called.
https://getintra.org/ is the only DNS client I know of that doesn't leak DNS connections over TCP, most other DNS apps (including the 3 mentioned here) do. Blokada is marked with anti-features tag by f-droid for telemetry: https://gitlab.com/fdroid/fdroiddata/-/merge_requests/8536 (Note: Intra, though open-source, has telemetry in it too).
AFAIK personalDNSfilter lets your route the DNS however you want. Not that it matters too much to me. I'm not trying to have airtight privacy, I just don't want to be buggered by trash. I'm interested to see your fork, though.
I'm using Netguard on Android devices I don't want to root and it's been good. Plus it does per-app firewalling as well.
[1]: https://www.zenz-solutions.de
[2]: https://netguard.me
[3]: https://blokada.org