After the latest stable firefox upgrade to version 68.6 I again started seeing DNS queries for Pocket related domains. I found this in prefs.js:
user_pref("browser.newtabpage.activity-stream.section.highlights.includePocket", true); I am not sure if this setting was new with this version or if firefox just started acting on it now, but in any case I am adding it to my user.js with a value of false, right now. -- Ian