I actually think I know what you mean, in a literal sense. Like, my dreams are so real and then I wake up and everything feels fake.

Derealization (sometimes abbreviated as DR) is an alteration in the perception or experience of the external world so that it seems unreal. Other symptoms include feeling as though one's environment is lacking in spontaneity, emotional colouring, and depth. It is a dissociative symptom of many conditions.

That's what I've attributed this feeling to, at least. Don't know if it's the same for you.