Unknown Mozilla dev addon "Looking Glass 1.0.3" on browser

> What's happening? Are you a fan of Mr Robot? Are you trying to solve one of the many puzzles that the Mr Robot team has built? You’re on the right track. Firefox and Mr Robot have collaborated on a shared experience to further your immersion into the Mr Robot universe, also known as an Alternate Reality Game (ARG). The effects you’re seeing are a part of this shared experience.[0]

EDIT: looking at this[1] comment, perhaps it's not a promo?

[0]: https://support.mozilla.org/en-US/kb/lookingglass [1]: https://www.reddit.com/r/firefox/comments/7jh9rv/what_is_loo...

> No changes will be made to Firefox unless you have opted in to this Alternate Reality Game.

Also, from the same page for those that appreciate irony:

> One of the 10 guiding principles of Mozilla's mission is that individuals' security and privacy on the internet are fundamental and must not be treated as optional. The more people know about what information they are sharing online, the more they can protect their privacy.

That can't possibly be true. I had it installed, and I'm on my work machine using Firefox Developer Edition. I didn't opt in to any ARG.