Ask HN: Why has Super+Printscreen suddenly started switching between ttys?

I have had a shortcut set up for multiple years with <Super><PrintScreen>. Today I went to use the shortcut and it switched me out to a virtual console. After playing with it more, it seems that it toggles between the two most recently used consoles.

Where would this be set up? Seems like something pretty low level, since it happens even outside of X.

Running Debian unstable if that is useful.