Comment by mozvalentin

You can actually see all of the telemetry data Firefox is sending by going to about:telemetry in your browser. You can also see all of the probes it could be collecting here: https://probes.telemetry.mozilla.org/ Keep in mind that the telemetry that is captured in Firefox goes through a thorough review process, so that it respects user privacy: https://wiki.mozilla.org/Data_Collection