Installing the latest Feb 2024 update (~1.2G in size) caused Manjaro KDE to hang during boot. Temporarily disabling “quiet splash” in GRUB during boot revealed that the hang was related to Plymouth (plymouth terminate.service?). Fortunately I had created a recent backup, which I restored and booted from. I then removed plymouth from etc/mkinitcpio.conf, ran “sudo mkinitcpio -P” to generate a new initramfs, and masked all plymouth services that were reported as running by “systemd-analyze blame”. After making the aforementioned changes I rebooted, and proceeded to install the update, with no issues noted.
For reference, I did NOT uninstall Plymouth from KDE, I just disabled it. Nor did I have any issue updating Manjaro XFCE or Gnome, only KDE.