On KDE and things like opening app on active monitor / desktop work fine. Only complaint is that on older versions, the taskbar on secondary monitors would sometimes disappear.
For reference I have 3 monitors (2x 4k, 1x 1080p) and am currently using Debian / Wayland and Ubuntu / X11.
It was a bug. I have 3 screens, and it would disappear on the third. An update, sometime around middle of last year fixed it, if my memory is correct.
But, I still have occasional problems with my monitors not waking up when I return to my desk. With 3, I've never had all 3 fail to wake, and a simple disable in the monitor settings, then choose "revert" usually brings them back.
For reference I have 3 monitors (2x 4k, 1x 1080p) and am currently using Debian / Wayland and Ubuntu / X11.