I’ve just made major changes with plymouth 22.02.122-17 that removed the old unneeded cruft in preparation for the new upstream v23.51.283:
WARNING: The plymouth-encrypt and sd-plymouth hooks no longer exist in the package. You should replace them with encrypt and plymouth hooks in your mkinitcpio.conf. The lxdm-plymouth.service, lightdm-plymouth.service and sddm-plymouth.service systemd service files no longer exist in the package. You should enable lxdm.service, lightdm.service or sddm.service instead.