Horizontal banding can be caused by a few things
- the slicer making the nozzle move differently between layers because there are different features in different layers. You can usually see this in the sliced gcode preview with something like nozzle speed
- inconsistent extrusion due to variation in hot end temp and/or filament width
- lead screw wobble. This will show up as a repeatable pattern along the z axis
- binding in the z-axis
- something loose, most likely on your gantry
If you print two different models and it happens at the same z height you can basically guarantee it's a mechanical issue. If it's more random you'll need to troubleshoot further.