Icons on the desktop are always pre-selected

All icons on my new 4.20 based desktop are pre-selected. In order to de-select them, one has to click anywhere on an empty space on the desktop, but switching to another virtual desktop selects them all again. Switching back to the former desktop, on which I de-selected all of them already, makes them pre-selected again.

This used to be different on my 4.18 based desktop.

Is this a new configurable item which had been introduced after 4.18? If so, how can I achieve the old behaviour again?

This happens on openSUSE_Tumbleweed with packages from OBS.