When I move or scale objects, keyframes are being added When I move, for example, my camera's view to a different place on the timeline, keyframes are being added even if I don't press i. Same thing if I move or scale an object. It never happened before, so I've probably changed a setting but I don't know which?!
Seems like you accidentally enabled Auto Keying. In the Timeline, uncheck the first icon (the circle) of the animation controls :