Found this thread as I’m experiencing exactly the same issue. Although there is very minor z-banding on smooth featureless walls, it’s far worse when there are holes or depressions which cause these horizontal ghosting bands.
I’ve literally tried everything already mentioned in this thread including the infill/wall overlap from the default 15% in increments all the way down to -5%.
Nothing makes it worse or better. AP and flow calibrations both automatic and manual with different values circling around the apparent manual optimals. Different speeds down to very slow. Different numbers of walls. Different infill, inner wall, and outer wall ordering.
Belt tensioning. z-rod vertical free play check (none at all).
Brand new hot end and extruder. No difference.
Different filament types, temperatures, etc.
Hundreds of test prints. Nothing changes it. The sad thing is I have a 6 year old QidiTech one-x that prints the test cube with the hole through the center perfectly but my brand new x1 carbon looks like craps.
Tech support has been making suggestions of different thing to try but nothing has worked.