This bug seems to have been fixed. Based on /usr/share/doc/firefox/changelog.Debian.gz this might have happened for the release of firefox 58 in January 2018.
** Changed in: firefox (Ubuntu) Status: Confirmed => Fix Released -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to firefox in Ubuntu. https://bugs.launchpad.net/bugs/1028266 Title: firefox license change not reflected in /usr/share/doc/firefox/copyright Status in firefox package in Ubuntu: Fix Released Bug description: Now that firefox (and thunderbird) have switched from the MPLv1/GPL/LGPL tri-license to MPL 2.0, /usr/share/doc/firefox/copyright should reflect this. Also, /usr/share/doc/firefox/MPL.gz should be updated, or removed if the MPL 2.0 would be included in /usr/share/doc/firefox/copyright. Also, based on a quick look, the license list in this file seem to lack quite a few of the licenses in the list one can see at about:license (help -> about firefox -> licensing information). This is for firefox 14.01 in Ubuntu 10.04 and 12.04. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1028266/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp