Is Professor Trelawney's divination deceptive or true? (Harry Potter)

She has been predicting that Harry will die, which is obviously not true. However, the descendants of the aristocratic family with the most predictive ability, people with vision, are good at predicting. For example, in the fifth part, it was predicted that Umbridge would be in danger, and Umbridge was killed in the forbidden forest. For example, in the sixth film, Harry met Dumbledore when he went to see her. She said she saw darkness coming, Dumbledore was killed that night, and dark mark appeared in the tower of Hogwarts. Before Harry was born, he predicted that Harry would defeat Voldemort (of course, this prediction led to the death of Zhan Mu and Lily to some extent). Trelawney made many accurate predictions, all of which played a key role in the book. I think Rowling wrote Trelawney as a liar's prophet in order to make readers doubt what she said, including those parts that suggested the plot, make the whole book more confusing and make readers feel suddenly enlightened after reading it.