The Mozilla Foundation's Coral Project has a full-time team building an open source comments system with no ads. Follow the repo, forum, and/or slack for updates. https://github.com/coralproject/talk
https://coralproject.net/
Also, it would be nice if they supported a SQLite backend, which would probably make more sense for small blogs running on very weak shared servers.
https://github.com/skx/e-comments/
You can see them in use on my tweaked site, e.g: