The KDE Plasma 5.21.5 point release is here to improve Wayland support by fixing a crash the occurred in the Plasma Wayland session when dragging a file over the panel and to position maximized GTK app windows to no longer be too high.
Not Wayland related, but comboboxes in GTK apps now use the correct drop-down arrow icon. The new Plasma System Monitor app has been improved again in this point release to no longer crash when selecting a new display style for any of the sensors, as well as to no longer lose the names of processes after modifying columns.