Hi there,

whenever I press Ctrl+Shift+A virtual screen #6 gets active. There's a Java desktop application running and a Konsole window.
When I press Ctrl+Shift+A again the Java application disappears but not the Konsole window. When I press Ctrl+Shift+A again the Java application gets visible again.

But I cannot find a shortcut which does this in system settings.

When I close the Java application the effect disappers (switching doesn't happen anymore when I press Ctrl+Shift+A).

Does anybody know what happens here?

My KDE version is 5.67.0 (Qt 5.13.2).

Ctrl+Shift+A is a Standard Shortcut meant to Deselect items. It's likely the Java application did overrun it, so the blame is on that application I think.