Since a week or so (maybe since kernel 5.12) one of my laptops with tumbleweed
hangs at shutdown with a systemd message telling me it is waiting for
networkmanager to finish. The only thing that works to come out is a forced
shutdown with the power button, not really nice for my SSD.
As a workaround I found is a shutdown script in Plasma "nmcli radio wifi off"
after which the shutdown completes without problem.
This happens on one laptop, a newer one with basically the same system doesn't
have a problem, but in both systems I find in journalctl the following:

mei 06 13:27:16  systemd[1]: iscsi.service: Succeeded.
mei 06 13:27:16  systemd[1]: Stopped Login and scanning of iSCSI devices.
mei 06 13:27:16  systemd[1]: Stopped target Network is Online.
mei 06 13:27:16  systemd[1]: Stopped target Network.
mei 06 13:27:16  systemd[1]: Stopping Network Manager...
mei 06 13:27:16  systemd[1]: Stopping Network Service...
mei 06 13:27:16  NetworkManager[1318]: <info>  [1620300436.7159] caught
SIGTERM, shutting down normally.
mei 06 13:27:16  NetworkManager[1318]: <info>  [1620300436.7165] device
(wlp2s0): state change: disconnected -> unmanaged (reason 'unmanaged',
sys-iface-state: 'managed')
mei 06 13:27:16  systemd[1]: systemd-networkd.service: Succeeded.
mei 06 13:27:16  systemd[1]: Stopped Network Service.
mei 06 13:27:16  systemd[1]: Requested transaction contradicts existing jobs:
Transaction for systemd-networkd.service/start is destructive (shutdown.target
has 'start' job queued, but 'stop' is included in transaction).
mei 06 13:27:16  systemd[1]: systemd-networkd.socket: Failed to queue service
startup job (Maybe the service file is missing or not a non-template unit?):
Transaction for systemd-networkd.service/start is destructive (shutdown.target
has 'start' job queued, but 'stop' is included in transaction).

After this last sentence on the problem system I get a dump of the iwlwifi and
the system is hung waiting eternally for the networkmanager to start again. I
haven't found where the contradictory command is found, have been looking
through systemd service files to no avail.
Any help would be appreciated.