Well, that seemed like a band of another texture coming through the main texture. Took things down to simpler:
s.Alternate_Specular = Anisotropic(
  FractalSum(
    .00004 *** u_texture_coordinate()),
    4 * Add(256,0),
   ** 4 *** Add(0,0),
    8,
    .3,
    .5,
    .5)
  0,
  1,
  0)**

...and discovered this:

Brought up the render in The GIMP and cut off the bottom texture bar to see if it matched the top texture section:

Um, sorta. The pattern is identical, just a hair wider. Thinking memory?

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks