Roughly, anything that can be used as an information carrier is limited by the speed of light (a good rule of thumb is that such things have some mass or energy). Things that can not be exploited on their own for information transfer do not need to obey that limit (stretching of space, entangling of particles, maybe other things).
PS It is an open question how that does not lead to contradictions when you start considering energy density of the vacuum or the extremely small gravitational waves (which can in principle transmit information) created by the changes in the latter systems. But these effects are astronomically small and it is difficult to imagine even a thought experiment that can detect them.
PS It is an open question how that does not lead to contradictions when you start considering energy density of the vacuum or the extremely small gravitational waves (which can in principle transmit information) created by the changes in the latter systems. But these effects are astronomically small and it is difficult to imagine even a thought experiment that can detect them.