There's a plot point in one of the sequels to The Three Body Problem like this. Certain spacetime-warping propulsion technologies turn out to leave behind a large mark in spacetime which isn't directly harmful, but is easily detectable even at stellar distances. Because of the Dark Forest theory, such a mark is taken as a giveaway of a careless and technologically dangerous civilization, which causes other advanced civilizations to immediately try to kill the civilization that made the mark before it can advance further or launch its own attacks.