I just verified that Firefox in the guest account on Xubuntu 16.04 Xenial works fine, but Firefox in the guest account on Xubuntu 22.04 Jammy does NOT work. So this bug is NOT a duplicate of bug #1593407 ! It is a new bug in Xubuntu 22.04 Jammy.
I just verified that Firefox in the guest account on Xubuntu 16.04 Xenial works fine,
but Firefox in the guest account on Xubuntu 22.04 Jammy does NOT work.
So this bug is NOT a duplicate of bug #1593407 !
It is a new bug in Xubuntu 22.04 Jammy.