Under Wayland, the session is not restored upon reboot, even when the "Restore previous saved session" is selected in system settings.
STEPS TO REPRODUCE
1. Start KDE Plasma under Wayland.
2. Open some applications (konsole, kedit, Dolphin, etc.).
The previous session is not restored.
The previous session should be restored.
Linux/KDE Plasma: Arch Linux
(available in About System)
KDE Plasma Version: 5.22.5-2
KDE Frameworks Version: 5.85.0
Qt Version: 5.15.2
This is expected at this point, see errata
*** This bug has been marked as a duplicate of bug 436318 ***