The confusion stems from the fact that laymen use force and mass interchangeably as they are always on earth and changes in altitude aren’t significant enough to worry about. Standing on a European scale and seeing a measurement in kg isn’t entirely accurate- it’s actually measuring Newtons and implying your mass in kg from that. Standing on an American scale, however, is literally measuring your weight in lbf. However, there is also a confusing unit called lbm or pounds mass which measures the mass of a 1lbf weight object on earth. The average person will never use lbm realistically, but this is technically the unit that converts directly to kg.