Using either KeyCastr or Karabiner Events Viewer, I can see that my Logitech MX Master 2S's "gesture button" invokes a ⌃⌥⇥.
Surely this is something past me has done to present me for some reason, but I cannot remember what it was — nor how I set it up.
I have looked through all the macro, automation, and UI input modification tools I can think of and have not found anything that remaps the button to those keys.
Is there anything I can do to investigate this further?
My next step is to see if the mouse behaves the same way on other devices, which I suppose would indicate that it has somehow been remapped on a firmware level...