The license for this add-on is falsely stated here as GNU GPL 3.0. This add-on in fact also includes two proprietary (non-free, not open source) third-party software products, as stated on the add-on's github page (https://github.com/disconnectme/disconnect). Claiming that the add-on is free software and licensed exclusively under GNU GPL 3.0 is highly deceptive, dishonest and inaccurate. Please rectify this and include the licenses of all software parts of the add-on on its official Mozilla Firefox add-ons page.

I've now reported this issue to the authors, to amo-admins@mozilla.org, via the form on its AMO page and on Mozilla's forum (https://discourse.mozilla.org/t/information-about-add-on-stated-incorrectly-by-authors-on-amo/23377). All with no effect, the mistake remains. Apparently any add-on developer can just claim anything they want about their add-on, there is no control. It's good to be aware that addons.mozilla.org can't be trusted and doesn't really care to provide accurate information about add-ons.