Well....THAT explains it! But why???

That spring cup appears badly deformed. It looks like it got fired outta there by a cannon. If it is, then you have a hydraulic pressure mismatch.

I bet it happened in reverse.
or the band broke

In manual low, the factory pressure there is around 55psi, but in
reverse there is no pressure regulation, so that servo sees whatever the pump puts out, which is spec'ed at ~250@1600rpm. The hi-pressure relief on the factory VB is set to 275psi .If that piston is 2 inches in diameter, then 275 psi is 864 pounds of force. Ima thinking that spring cup just gave up. Better check your hi-pressure relief system.Or your regulator valve which controls the pressure below the 275 relief.
If the relief is stuck, and the idle is very high, I have no idea how high the pressure could get to be.