Subtract one image from another with Google Earth Engine and getting too high values

I’m trying to apply Change Detection with Google Earth Engine by subtract one image from another and getting too high values in the new image although there is low values in both images

select_Image = select_Image.select('LSWI').subtract(image_XT_ctrl.select('LSWI'))

the selected image (the one i subtract):

the Ctrl image (the one i subtract from):

the result: