The menu is no longer there, AFAIK. I have not spent much time looking for the feature, to be honest, and I no longer keep Firefox installed except when testing

The menu is no longer there, AFAIK. I have not spent much time looking for the feature, to be honest, and I no longer keep Firefox installed except when testing, so I won't look for its existence now. (I usually apt install before testing and apt remove after, because otherwise it often becomes the system default.)