It's hard to tell, but it could be the machining. If there is a sharp corner at the base of the bearing register, it could cause a stress riser, letting a crack start, and progress until failure.
Wheel hop is most likely from a standing start, where the rear tire literally hops or chatters do to suspension compliance. On a track car I think more of curb hopping or dropping wheels, letting the rear tire spin-then grip, shocking the drivetrain.
Wheel hop is new to me, I do at times during a race go to far up a curb in a corner which will make one rear wheel go up an return to the ground - is this wheel hop? Is this something that will brake an LSD?
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Kroggers...
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It's hard to tell without being in the car, but these are not high power cars. If it's significant, you should be able to feel the car "lurch". From that link, it sounds like it could be a manufacturing issue.