Garnet can only see specific details. Like a future she wants to see. She couldn't see a future where they caught peri and didn't know that in the future Pearl would lie to her. So maybe she has probability powers and slight future powers. Sapphire has future powers. I think that the reason garnet has probability powers is because of Ruby. Ruby is impulsive so it messes with sapphires power and makes her see multiple instead of one correct one.