Man, I don't understand this sentiment at all. I don't know what would be different from my setups, but KDE has always been rock solid for me. Back when I used it on Mandrake Linux and today.
KDE on Arch + Nvidia Wayland was a buggy experience for me a few months ago. But honestly, even X11 on Intel integrated graphics gets a few buggy releases every couple months.
I had KDE on Arch with Nvidia Wayland going pretty well on Lenovo ThinkPad with a 4070 in an eGPU, until an update borked it. The only thing I couldn't figure out was hot plugging my laptop dock, and not having the integrated Intel pick up in absence of the eGPU. But taking Nvidia out of the equation resolved all that. I then picked up a Radeon 6650, and I can't even get the stupid thing to fire off at all.
I think I'll be better served just building a dedicated rig for my multi monitor desk setup.