All the incognito browser windows share the same “session” in Firefox. So say you open an Incognito window to browse Facebook or something, then you open another Incognito window, this new incognito window is linked to the previous incognito window, meaning you are logged into Facebook at that new Incognito window as well. This is because, as I explained before, all the incognito windows share the same “session”
The only way to clear incognito window is to close ALL of them and then create a new incognito window. You dont have to close the main non incognito Firefox window though, just close all the incognito windows. Then open a new one, now your previous session is destroyed and you are new again.
You may know it but its not that common knowledge as it should have been
For me that behavior was expected. E.g. if I open a link from incognito in a new window, then it obviously should also use incognito but share its context with the previous sessions, otherwise it would require you to login over and over again. If an independently opened incognito window behaved different from a link-click window, I’d find it even more confusing.
I would say it should be the opposite. Separate windows should be independent but tabs on other hand can share same session.