I wrote a script to handle some tasks on a remote server before the network
connection on my workstation goes down and put the script in
/etc/NetworkManager/dispatcher.d/pre-down.d. The script logs all its actions to
the journal.

When i close my network connection manually (with plasma5-nm-applet) i can see
in the journal that the script gets executed correctly before the network
connection is closed.

However on system shutdown the script is not executed at all although all
network connections are terminated on a shutdown.

"man NetworkManager" and
"https://developer.gnome.org/NetworkManager/stable/NetworkManager.html" both
say

"pre-down
The interface will be deactivated but has not yet been disconnected from
the network. Scripts acting on this event must be placed or symlinked
into the /etc/NetworkManager/dispatcher.d/pre-down.d directory, and
NetworkManager will wait for script execution to complete before
disconnecting the interface from its network. Note that this event is
not emitted for forced disconnections, like when carrier is lost or a
wireless signal fades. It is only emitted when there is an opportunity
to cleanly handle a network disconnection event."

I consider "shutdown" not to be the sort of "forced disconnection"
mentioned in those manuals. Therefore i think it is NOT correct that the script
is not executed before the network connection is closed on system shutdown.

My system runs openSUSE Tumbleweed 20191023 but i can see the described
behavior
on systems with openSUSE Leap 15.0 and 15.1 as well.

I believe to vaguely recall that somewhere in the past (openSUSE Leap 42.x ?)
the script used to be executed correctly even on shutdown.