It could mean that the value itself was already incorrect and your change now implies that you have checked that it is now correct. One random example: Metal can have many colors, but this hydrant cover is not gray in any world: https://www.openstreetmap.org/node/12252900170
https://www.mapillary.com/app/user/WFOberweyer?menu=true&lat=50.4585118&lng=8.091218099999992&z=17&pKey=1624717521790760&focus=photo&x=0.5173033829709038&y=0.5068994507245498&zoom=1.6012900049542125