The issue you're describing, where the cab of your Kubota Excavator moves in the same direction as the boom when you swing it left or right, may be related to a problem with the swing motor or the hydraulic system. It could be caused by a hydraulic valve issue or an internal leak in the hydraulic system. Additionally, check for any damaged or misaligned linkage between the cab and the boom. It's essential to have a qualified Kubota technician inspect and diagnose the problem, as working on hydraulic systems can be complex and potentially hazardous without the necessary expertise and equipment.