I'm so sick of people saying how Harry and Hermione "changed time"
They didn’t change time.
They didn’t bring Sirius and Buckbeak back to life.
Sirius never died.
Nor did Buckbeak.
They had already gone back in time. Hermione almost fucked up and saw her future self in the forest behind Hagrid’s. Harry saved himself, and assumed it was his father because he was always told how much he looked like James.
These events were the same in both timelines. Neither were different.
All Dumbledore did was send Harry and Hermione back in time to make sure the events actually happened and the timeline was fulfilled.