Review FF release notes from FF69 to latest (FF78)
Release Notes: https://www.mozilla.org/en-US/firefox/releases/ Developer release notes: https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases
Also, diff prefs.js between latest and esr 68.
Also look at the bugs from 69 to 78 (update target_milestone param for each version)
Mozilla fixed: https://bugzilla.mozilla.org/buglist.cgi?query_format=advanced&resolution=FIXED&target_milestone=mozilla69&order=priority%2Cbug_severity&limit=0
Mozilla reponed: https://bugzilla.mozilla.org/buglist.cgi?resolution=---&query_format=advanced&target_milestone=mozilla69