I don’t know when it started exactly. But I think Firefox 60+ is affected by this.
Many months ago I wanted to set up a new Firefox (WebEx) for long term use. After install I did not permanently allow Firefox “as Webbrowser” in my Firewall, just in case I forgot to disable some privacy invading feature. Obviously the fresh install created lots of popups.
I then went ahead and started disabling everything related in options and about:config. This reduced firewall popups, but there would still be a popup - at startup, and every now and then when left idle in background.
I spend days searching the web for solutions, implemented the most restrictive user.js I could find. Made any changes I could imagine to be remotely related. Finally frustrated and desperate I ended up going delete-crazy on about:config, probably breaking the browser itself.
Yet, the firewall would still report Firefox making outbound connections, while idle with blank page.
I gave up, reinstalled. Since then I have a Firefox install for which I have to allow every single connection it wants to make. It is pretty damn annoying. And because of the multiple IPs necessary for some websites, I can never be sure. I might occasionally allow one of those connections not initiated by me by accident.
I wonder if any of you can replicate this issue; know how to solve it.