Hey man, I just took a look and:
Looks like the 3D noise shaders usually don't behave super predictably when using a 2d projection to control its frequency, specially circular 2D shapes (using a linear ramp is more 'stable').
I started to investigate first the Z axis that visually is the one that is being distorted on your renders, but I found that it wasn't the direct cause of the problem.
The issue was coming from the axis that is apparently don't affect that much this top surface, which is the Y axis. So, after some testing I found out that the hack is: multiplying the Y axis scale value (eg. in the case of the aiNoise) for a number at least more than 10x the value of the others.
This may not clear absolutely all the distortion, but for sure decreases it a lot.
In this case I used the value 10 for the Y and 0.8 for the other two: