Currently restoring system tray does not work on Wayland.
Even with this commit, the functionality is still worse than on X11 because clicking on system tray does not hide application window.
Well, basically when you click on any KF5 application (e.g. Konversation, KGpg, Akregator, etc...) in the system tray, nothing happens.
This does no happen with Qt5-only programs. Clicking on system tray there always brings the window up.
From what I can see in the code, on X11 KWindowSystem::activateWindow(associatedWidget->winId()); raises the window
but if I understand correctly KWindowSystem::activateWindow can never work on Wayland. This is clearly not what end user