(win11) Since the last version of firefox:
1. when you are downloading a huge file which takes time,
2. and you will close the main firefox window, but will leave the downloading window
3. when you reopen the firefox through desktop shortcut, the bookmarks side panel will not open (crtl + B doesn't work, opening it through options won't work).
I've been working like this for years, this is a new bug since a week(s) (?)
