There is a new merge on the Wayland GitLab repo. This new merge (of an old pull request) adds xdg-session-management protocol to Wayland. This is a big development and certainly a feature Linux users will enjoy.
As per the brief message in merge request:
For a variety of cases it’s desirable to have a method for negotiating the restoration of previously-used states for a client’s windows. This helps for e.g., a compositor/client crashing (definitely not due to bugs) or a backgrounded client deciding to temporarily destroy its surfaces in order to conserve resources.
This protocol adds a method for managing such negotiation and is loosely based on the Enlightenment “session recovery” protocol which has been implemented and functional for roughly two years.
In simpler words, session recovery is finally coming to Wayland.
Yeah, it’s inconsistent. KDE / QT apps should reliably restore to the right desktop / activity and position. But non-KDE apps like GTK & Electron apps are not consistently restored depending on the app. Instead it depends on work arounds on Wayland and apps can still erroneously open on the current screen / desktop instead. This can be still be managed with Kwin with more workarounds - for example specific rules can be applied in Kwin for really problematic apps if users want - but its faffy.
So this is definitely a welcome change to wayland.