I looked up, what I found is the Mozilla Information Trust Initiative (which happened soon before they gloated about how cool their new "curated news system" was, and how it didn't infringe on privacy).
August 2017
Mozilla Joins George Soros’s Efforts In Launching A Strike Against “Fake News”
Mozilla and fact-checker engine join fight on fake news
>The US-based open source group said it was "investing in people, programs and projects" in a new initiative to actively "disrupt misinformation online".
>It said the "internet's ability to power democratic society suffers greatly" because of fabricated stories
>The group, which is backed by Omidyar and Hungarian-born investor and philanthropist George Soros, said its software is capable of spotting lies in real time, and was used to fact-check a live debate at the House of Commons.
http://archive.is/09j03
http://archive.is/knFbZ
January 2018
"Mozilla Firefox is testing updates that customers fear pivot from its focus on consumer privacy"
https://www.businessinsider.com/mozilla-firefox-testing-updates-consumer-privacy-2018-1?r=US&IR=T (sorry, can't archive)
>Mozilla is currently testing two updates on its Firefox web browser, including a better recommendation tool and sponsored content.
>Both new features are attempts to experiment on popular browser functions Mozilla thinks can be done better and more securely, but they still require sharing data.
>In October, Mozilla informed users that it would be testing a recommendation tool that would collect data and share browsing activity with servers owned by its newly acquired company, Cliqz GmbH. A few months later, in an update on Mozilla's acquisition of website-bookmarking application Pocket, the company announced Firefox would "soon experiment with showing an occasional sponsored story within the Pocket Recommendations section," according to the press release.
http://archive.is/PFXKJ (Testing Cliqz in Firefox)
http://archive.is/9qodi (Update on Pocket and Firefox Integration)
>"Pocket recommendations and sponsored stories were implemented in a privacy-centric way. Neither Mozilla nor Pocket receives any of your browser history to make this experience possible"
>"Users get great stories from the web that are relevant to them, without having to trade their privacy in return."
And then, some articles explaining that some telemetry parameters were being removed (which implies they were activated before).
November 2017
Firefox 58: Mozilla will collect only base Telemetry data (release channel)
>Traditionally, Mozilla collected two sets of Telemetry data of its Firefox web browser: base Telemetry data that was on by default and could be disabled by Firefox users, and extended Telemetry which was off by default for Firefox release builds and on by default for pre-release channels such as Beta or Nightly.
http://archive.is/Wd7l5
Does it sound like it, or was it something else entirely?