hm, the only thing that may have an effect to systemd is syncthing-bin - but - it updated smooth on my Jolla1 with the same stuff installed. Just broke the JollaC...

And the update to 2.1.1.23 worked without problems on both devices. And systemd was updated with that version?

The only thing I know which may hang a systemd service (since the last updates on debian) was a not existing pid file at a place systemd expects it. Than this service may hang on reboot and start.