Check the link I’ve provided above. It has been reported in December 2019.

It should be filled in - check the provided link above.

I do not know about any workarounds but you might have more luck searching for one.

As for other issues, someone mentioned in the issue that the “Disable touchpad while typing” is broken on Wayland too; however both of these issues are not present on X11. Only other issue I’m having is kde daemon crashing while running pacman -Syu inside Konsole (see this link). Other than that, I was with Plasma more than happy and had no other issues.

Unfortunately this simple trick does not work. It seems to be a backend issue too (not just missing button).