Edit: /etc/apparmor.d/firefox (410B)
# This profile allows everything and only exists to give the
# application a name instead of having the label "unconfined"
abi
,
include
profile firefox /{usr/lib/firefox{,-esr,-beta,-devedition,-nightly},opt/firefox}/firefox{,-esr,-bin} flags=(unconfined) {
userns,
# Site-specific additions and overrides. See local/README for details.
include if exists
}