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.