The move replaces SDDM but means giving up on custom login themes.

From their repo:

Plasma Login

Plasma Login provides a display manager for KDE Plasma, forked from SDDM and with an new frontend providing a greeter, wallpaper plugin integration and System Settings module (KCM).

What we want

  • Great out-of-box experience in multi-monitor and high DPI and HDR
  • Keyboard layout switching
  • Virtual keyboards
  • Easy Chinese/Japanese/Korean/Vietnamese (CJK) input
  • Screen readers for blind people (which then means volume control)
  • Remote (VNC/RDP) support from startup
  • Deeper Plasma integration including:
    • Display and keyboard brightness control
    • Full power management
    • Pairing trusted bluetooth devices
    • Login to known Wi-Fi for remote LDAP