Ubuntu 20.04 with all updates installed, Firefox snap of latest stable released version
GNOME Software app > Firefox snap > Permissions > Use your camera > ON
at the same time:
$ snap connections firefox
Interface Plug Slot Notes
camera firefox:camera :camera manual
Let’s change this setting as next:
GNOME Software app > Firefox snap > Permissions > Use your camera > OFF
at the same time:
$ snap connections firefox
Interface Plug Slot Notes
camera firefox:camera - -
Similar behavior for Avahi interface (I guess all remaining too) - slot side gets manipulated.
Actually setting in GUI is placed in Firefox snap entry, Software ap. For myself it looks bit weird for engine under hood to manipulate interface slot-side. Interface slot-side is under control of other snap or resource controller not the Firefox snap. Reasonable would be to modify plug-side on changes of shown app snap setting.