My suspicion is that this is a false-positive.
If you go to about:config and search for doubleclick there is an entry called: browser.urlbar.doubleClickSelectsAll
Firefox for Android, Firefox for iOS, Firefox Rocket and Firefox Focus collect data about installations and retention using a third-party tracking framework called Adjust and Leanplum. This helps Mozilla determine the origin of the installation by answering the question, "Did this user on this device install the application in response to a specific advertising campaign performed by Mozilla?"
Use is self-explanitory in the name.
This twitter thread indicates same:
https://twitter.com/rnewman/status/934861503630643204
Also, LeanPlum is explained here:
https://support.mozilla.org/en-US/kb/send-usage-data-firefox...
Quote:
Firefox for Android, Firefox for iOS, Firefox Rocket and Firefox Focus collect data about installations and retention using a third-party tracking framework called Adjust and Leanplum. This helps Mozilla determine the origin of the installation by answering the question, "Did this user on this device install the application in response to a specific advertising campaign performed by Mozilla?"