Please see here: https://wiki.archlinux.org/title/Plasma#Installation
To enable support for Wayland in Plasma, also install the plasma-wayland-session package. If you are an NVIDIA user, also install egl-wayland, and if the session does not start with the proprietary nvidia driver, also enable the DRM kernel mode setting. If that does not work, too, check the instructions on the KDE wiki.
I am not an Nvidia user, so I can’t be of much help in that area.