I was supposed to always be like this, but there was a bug in MW earlier that made legacy scale with the coefficient. Not sure exactly when it was fixed, but some time in the last 3-4 months I think.
It's only the same if you set the FOV to 65 Hdeg 4:3 (which is 80.690944 configured in the game). Legacy is locked to scale to this FOV while relative will scale to the configured FOV.