Actually, funny coincidence, but I've narrowed it down to the GestureSlider preset (Touch & Slide buttons for brightness & volume.) which happens to be your extension. But yeah, I'm not seeing it and don't know why this is still happening
EDIT: Eventually I found the setting buried in the old configuration ui. There was indeed an active global shortcut enabled with that setting. Maybe it wasn't GestureSlider, but I'm not entirely sure