ConfigurableJoint target rotation, Y was applied after X "in order", but Z was applied "independently"

I think there might be a bug in Unity’s ConfigurableJoint target rotation X Y Z angles. I have tested using the Active Ragdolls project as a base.

If I change the shoulder joint’s X rotation it pivots around X as expected. Then, I change the Y rotation, and it pivots around the new Y axis AFTER applying the X rotation. However, then, I change the Z rotation, and it pivots around the original Z axis completely ignoring the previous rotations. Thus there is a difference between how it treats Y rotation vs Z rotation. Y axis depends on the X rotation, but Z axis is independent of all other rotations.