I have reviewed the service, and it works very well for me (in fact, on my linux, it worked better than Quad9. With Quad9 sometimes I had sudden leaks, while, as far as I tested (I spent 2 hours testing, restarting the computer, restarting the network, activating protonvpn…) blahdns did not fail me and there were no leaks even once).
I have seen that you use Hardenize to analyze the webs, so I send you the link/analysis of the page:
I also send you its github page: GitHub - ookangzheng/blahdns: A small hobby ads block dns project with doh, dot, dnscrypt support.
Finally, I leave you directly their website, in case you want to take a look at it: https://blahdns.com/
DISCLAIMER: THIS SOFTWARE IS CURRENTLY NOT RECOMMENDED BY PRIVACYGUIDES. IF YOU WANT A RECOMMENDED DNS SERVICE, GO TO THIS WEB SITE.