Unfair manager

My manager treats me unfairly. He hired several of his fellow alumni from the same university and treats them with favoritism even though my work metrics are better. When I complained about this, he wasn't going to do anything, so then I tried to transfer to another manager. My manager decided to put me on a PIP right away after I submitted my transfer request. Then the PIP was put through the Pivot program but the managers evaluating the situation were all friends of my manager.

I am really stressed out. Why did Amazon change the transfer policy to not allow managers to block transfers if they can still block it with a PIP right after the transfer request? I think this is the same reason another employee facing my situation tried to jump out of a building last year because he was blocked from transferring. And what's the point of the Pivot process if the people who are supposed to be neutral are just friends of my unfair manager?