To opt-out or not to opt-out - that is the question

[NewKidOnTheBlock]

1. Telemetry Opt-Out

Firefox Telemetry Coverage ping is a diagnostic tool used to determine whether Telemetry is functioning for users. This preference must be manually created to prevent the coverage ping from being sent. The coverage ping is sent once per profile and is not dependent on the standard Telemetry enabled preference.

The preference toolkit.coverage.opt-out and toolkit.telemetry.coverage.opt-out do not exist in the Firefox configuration.

https://www.privateinternetaccess.com/blog/mozilla-does-not-respect-user-requests-to-stop-tracking-telemetry-data/

So, according to this information:
toolkit.coverage.opt-out = OUTDATED, should be removed from Securefox, line 1403
toolkit.telemetry.coverage.opt-out = OUTDATED, should be removed from Securefox, line 1402

2. Fingerprinting Opt-Out

While digging through about:config, I found another opt-out toggle that's not featured in Betterfox (yet):
toolkit.telemetry.user_characteristics_ping.opt-out
Since Firefox is offering, we should take it and add it to Securefox.
Would you like to know more? https://groups.google.com/a/mozilla.org/g/dev-platform/c/K5ycPJ6ngrw

[yokoffing]

Thanks for reaching out!

toolkit.coverage.opt-out

toolkit.coverage.opt-out is still used in Arkenfox. I'll need to confirm that it is an outdated pref before removing. Until then, I defer to their expertise.

toolkit.telemetry.user_characteristics_ping.opt-out

The link you included says:

The new telemetry probes respect the existing Telemetry opt-out settings.

This means disabling the main telemetry switches already nullify toolkit.telemetry.user_characteristics_ping.opt-out. The next sentence goes on to say that if a user has not disabled the main telemetry switches that

They can also be disabled individually by setting “toolkit.telemetry.user_characteristics_ping.opt-out” to true

[Thorin-Oakenpants]

The preference toolkit.coverage.opt-out does not exist in the Firefox configuration

• https://searchfox.org/firefox-main/search?q=toolkit.coverage.opt-out&path=&case=false&regexp=false
  • --> https://searchfox.org/firefox-main/source/toolkit/components/telemetry/pings/CoveragePing.sys.mjs#19

The correct and documented preference is toolkit.telemetry.coverage.opt-out

• https://searchfox.org/firefox-main/search?q=toolkit.telemetry.coverage.opt-out&path=&case=false&regexp=false
  • ---> ¯\_(ツ)_/¯

[Thorin-Oakenpants]

https://bugzilla.mozilla.org/show_bug.cgi?id=1487578#c1

seven years old .. JFC

[NewKidOnTheBlock]

So both of them turn out to be long-abandoned placebos?
There were clues:

[Thorin-Oakenpants]

prefs do not have to be exposed in about:config - they are hidden until modified/set by the user/code. This is illustrated by simply opening about:config and checking the checkbox to only show modified prefs