That's worse.

The last thing I want is my browser popping something up when I'm AFK.

(Bug reporter here)

I don't know exactly what anyone else experienced. What I experienced is: I was away from my computer and noticed that my Syncthing[0] folders were out of date, so I used KDE Connect[1] to make sure Syncthing was running on my PC, which opens a tab connecting to Syncthing on the local machine in the default browser - Firefox in my case. Some time later, I unlocked my PC and found the advertisement on top of my Syncthing admin page.

So yes, it popped something up while I was AFK, though I can't guess whether it would have done so if I hadn't remotely triggered a new tab. Needless to say, I was very surprised to see that behavior from Firefox, and even more surprised that despite posts to reddit and HN complaining, I didn't find a report in Bugzilla.

[0] https://syncthing.net/

[1] https://kdeconnect.kde.org/

> seem to indicate that Mozilla intended for the popup to be shown if the user is AFK for 20 minutes

Wow, that would have been a whole lot worse than what actually happened!

This is a great way to freak people out and make them distrust you — move their stuff while they're not looking.