By default now Firefox for Android shares an extra link with TRACKING for advertising itself. This is the features that everyone loves.
Ok, buried in the menu there's an option to disable this shit. But it's infuriating that a "please spam my friends and track the opening rate of my links" option is enabled by default
Its a unique link that Mozilla knows is tied to your device, and can see what devices open the link. That is pretty invasive tracking.