Shadow at change of diam on one ob?

got this old file with PBR

in viewport and render it gives some shadow where there is a change of diam on column

may have to do with scale of noise
object has high Z and smaller X and Y!

why is this repeating this shadow at speudo joints on one object

i do have a little bit of world light but does not seems to affect the shadows!

tried with object or generated and still having these shadows

thanks for feedback
happy bl