Mass Effect 5 is set to follow the original trilogy, meaning that the ending of Mass Effect 3 will bear important repercussions during the new game’s start. All the endings for ME3 change the galaxy’s balance completely, but one, in particular, has some destructive effects on synthetic and organic life. The “destroy” ending, as it’s often dubbed, sees Shepard kill every AI life form in the galaxy by emitting a lethal pulse through the mass relays.

https://screenrant.com/mass-effect-relays-destroy-ending-op-ed/