I noticed that “incoming.telemetry.mozilla.org” is blocked by NextDNS when using Firefox with Arkenfox installed every time I start up the browser. Even though it’s being blocked at the DNS level I thought Arkenfox removed all telemetry?
Per one of the Arkenfox maintainers: “There’s nothing wrong with mozilla’s telemetry - it uses PRIO, and it uses GLEAN, and it doesn’t collect any PII, and it helps decisions upstream (and I’m not talking pedantic UI changes) that benefit everyone. Opt-in doesn’t work. I’m sure you can google why. There is no reason to distrust Mozilla here - you’re using their product” https://github.com/arkenfox/user.js/issues/1659#issuecomment-1518353397
That being said, if anyone wishes to block the telemetry you can do so by following the Arkenfox recommendations and setting up uBO: https://github.com/arkenfox/user.js/wiki/4.1-Extensions And/or a network wide DNS blocker (which OP did).
It does get rid of it all