Of the glass or of the water?
If it reduces the heat of the glass then the situation is made worse as it makes an even greater temp difference.
If it is the water, I doubt it has that significant an effect as spoons tend to have a large surface area to volume ratio meaning they will be about the same temp as the water within a second and wouldn’t take too much of the heat.
A more pressing question is why you would put hot water in a glass?