[Aachen]

It is. Telemetry turned off, all URLs removed from about:config, still making requests to "buckets/monitor/collections/changes/records" at the domain firefox.settings.services.mozilla.com (spotted this one in my proxy while trying to do a website audit).

[Deukhoofd]

Are you certain that is related to telemetry, and not a request for one of Firefox's other services?

[Aachen]

It constantly pings the servers with my IP address, timestamp, and user agent if nothing else. They can see where people are over time. I was busy so haven't looked into what it's sending (just exempted the domain from interception for the duration of the audit), but in the EU and IP address with timestamp is personally identifiable information.