I can still see parts of the desktop. They should really go all in and add some more blank space to the sides of the menu.

From PLMs GitHub:

Plasma Login is in a prototype state and is not considered ready for real-world usage.

I just tried it out anyway, because SDDM sucks. PLM no longer uses the lowest common resolution for all displays and HDR works about as well as it does in plasma (sometimes I get a black screen and have to turn the display off and on). Still better than SDDM. It also integrates with KDEs system settings so it’s easy to setup.

Auto-login does not work however, so I’ll be sticking with SDDM for now, but I’m looking forward to the stable release.