Randomness in the world

Hello, Michi. I didn't understand why, according to quantum theory, there is randomness in the world. When light is a wave, it is impossible to say where it is, but when you examine the position, its function breaks down, you can know the position probabilistically. But if it is probability, then it is not a random thing, because if it were truly a random thing, we would not have probability either (correct me if I am wrong). So where/is there randomness in the world?