Comment 9 for bug 1702601

Can you edit that file like how it is suggested in the first answer here:

https://askubuntu.com/questions/844108/dpkg-error-processing-package-unattended-upgrades

That person changed the header of the initscript to this, just below the shebang line:
### BEGIN INIT INFO
# Provides: PanasonicMFSlpd
# Required-Start: $all
# Required-Stop:
# Default-Start: 2 3 4 5
# Default-Stop:
# Short-Description: Panasonic scanner driver
# Description: Panasonic scanner driver
### END INIT INFO

I don't know what it was like originally, maybe it had plymouth in the required-start line.

Make a copy of the script, so you have the original one at hand if needed, and try the above change, see if it helps.