Here are a few issues I've had on KDE when I only had one monitor (all on KDE X11, KDE Wayland wouldn't launch on either Nvidia or AMD GPUs):

• "start" bar (whatever KDE calls it) gets stuck open, when I try to have it auto-hide; sometimes it stays open even when maximizing videos
• "win" key stops working to access the start menu, which is an option on the latest KDE (I used to use an extension in KDE4 when it wasn't an option)
• keyboard switcher bugs out and stays open after selecting a layout (I usually use Dvorak, my kids use QWERTY, so I switch often)
• sometimes locking my screen boots me out of my session into a new window manager login shell, and I lose my open windows; not sure how this happens, maybe my kids mash buttons, idk, but it happens 1-2x/month

I'm sure there are more.

With GNOME Wayland, my issues. are essentially limited to a weird rendering issue that resulted in my screen getting "cut" (as in, right half of my screen rendered down a pixel or two). That's it. Everything else works smoothly, and I haven't had any issues in the past 2-3 weeks since installing it.

None of the KDE issues were deal-breakers, they were just kind of annoying and made the desktop feel worse. I don't need really any features from my DE, I just need to launch apps full-screen and switch between them. That's it, and KDE failed at that without any extra extensions installed (just whatever ships with openSUSE).

So that's why I use GNOME. I think KDE is fine, but I honestly don't care what my DE does, provided it can launch and switch between applications. Once it's set up and doesn't look horrible, I generally don't touch any of the configuration options. I used to care about such things, but after 15-ish years with Linux, I guess the novelty has worn off.