`journalctl -u fwupd-refresh` will show failure lines below when the service is
trigerred by fwupd-refresh.timer: 



Jul 08 01:20:09 p72 systemd[1]: Failed to start Refresh fwupd metadata and
update motd.
Jul 08 01:26:16 p72 systemd[1]: Starting Refresh fwupd metadata and update
motd...
Jul 08 01:26:16 p72 systemd[1]: fwupd-refresh.service: Main process exited,
code=exited, status=1/FAILURE


It turns out this is caused by the DynamicUser=yes statement in
fwupd-refresh.service, causing the failure, as it has been found on:


https://github.com/fwupd/fwupd/issues/3037

A work-around  is to add 'User=root' statement as the last post of issue above
mentions.

systemd issue for DynamicUser:

https://github.com/systemd/systemd/issues/22737