making Firefox the most private and secure major browser
If calling home and to selected 3rd party analytics aren't part of the metric then yes, Firefox might be the most private. What proof, even they say they've telemetry.
Here's all the domain Firefox uses for telemetry: https://raw.githubusercontent.com/MrRawes/firefox-hosts/firefox-hosts/hosts
So much for privacy.
Just move to LibreWolf.