DNS provider? You can already change the DNS server in Preferences/Settings, so there is no need for Mozilla to operate its own DNS service.
I'm also pretty sure Firefox already warns users about dangerous websites.
Firefox includes some built-in content blocking features, and you can view the statistics at about:protections. More importantly, I don't think it's the browser's job to decide on behalf of the user whether ads should or should not be blocked. That choice should remain with the user.
