Whats Going On?

Never happened before. 1000 hours on this game so i guess its a new addition to the game but what is actually going on? Reaching near the room we dedicated to all of our trophies and relics, we get automatically the Black Out debuff and projectiles start shooting from the walls,but nothing's actually looking like its shooting them because they spawn from the edge of the screen and they follow you until you go away from the houses, almost reaching the surface. Anyone has any clue about what should we do?