Every piece of KDE software I've tried has been buggy to the point that it's now a red flag to me: Spectacle (silently failed to copy/paste), krunner (refused to close), SDDM (refused to login), Dolphin (ffmpegthumbnailer loops lagged out whole system, SMB bugs), System Monitor (wrong information), KWallet (signal fails to open, data loss)
I have had problems with Spectacle related to permissions on Wayland and I think I experienced the failed to copy bug once.
I have not had any other significant problems for some years - not since KDE4. I do not use SMB but everything else works fine and KDE is my daily driver.
Copy pasting images is often hit & miss.
Sometimes I have the image copied but it doesn't paste in the browser. However it can be pasted to GIMP. If I paste it there and copy it from GIMP then I can paste it to the browser.
So who's fault is that? Spectacle's or browser's? Maybe wayland's?
I am sure that people who use KDE can politely respond to your critique but I can say this that I used to use Kate for sometime and its really great.
Fun fact but Asahi Linux creator uses kate :)
Been using KDE for years and never had any of these problems.