greasy spots on my screen glass (or under it)

i bought a macbook pro from a person who sells used electronics, the previous owner used it for a very short time (like 6 months to 1 year) the previous owner took it to someone and they said that he got those spots from closing the laptop while its hot which sounds like a lie to me .

the spots look like grease really thick greasy, if you slide your hand on them they feel like normal glass so thats why i said that maybe they are under the glass, if the screen is dark (for example when watching a movie and it has transitions) or when its turned off they appear but as soon as light from any color but black comes on the screen they become invisible .

i tried wiping it with a damp towel and with a screen wetwipe but nothing worked

do i need to replace the whole screen or can i fix it myself