Holding Alt + MosueWheel Up/Down affects the size Scale multiplier of Constraints. This feature is not apart of the Keyboard and Mouse shortcuts menu and, to my knowledge, cannot be changed. Why? I haven’t found any documentation or explanation for why this feature exists.
As a Developer, hidden locked keybinds with no documentation makes plugin development and general workflow management difficult to predict. Please consider moving this hidden keybind into the official Studio Keyboard and Mouse shortcuts menu.