Summary Some players of Elden Ring's DLC have experienced a strange phenomenon in which their controllers seem to randomly vibrate as they're exploring the Land of Shadow. This takes the form of two quick pulses- one small, one large. They usually, but not always, occur outside battle, when the player isn't actively being hit by enemy swings that might normally cause such vibrations.
Elden Ring DLC's Random Vibrations May Be A Result Of The Bloodfiends' Battle A Random Encounter May Cause PS5 Controller Vibrations The simplest explanation for PS5 controllers randomly vibrating in Elden Ring's DLC is that they're triggered by the battle between Bloodfiends and Messmer's knights, which eternally rages on at the foot of the Ellac Greatbridge. The player doesn't have to do anything to trigger this fight: it just happens every time they load into the area.
It wouldn't be the first time FromSoft has included a detail like this in one of their games. Think of Mergo's distant cries in the later chapters of Bloodborne, or "The Beast Eye quivers" messages from base Elden Ring. These games are full of subtle details - armed only with the powers of observation and their repetitive nature, it's up to the player to infer what they could mean.