The header bar of Kickoff looks pretty crowded, having "Sleep, Hibernate, Restart, Shutdown" next to each other. Especially in languages with longer text it looks worse. Therefore I'd like to suggest to introduce an option to reduce these functions to icons only. An alternative approach could be to hide these functions behind a second button next to the 'leave' button. In order to reduce the hassle with clicking in a context menu, the area where the displayed apps grid/list normally reside, could be used to display a grid of the functions named above.
Luckily for you, this exact option was introduced in Plasma 5.23. :)