False utopia
Discovery of the dystopian truth is a plot frequent and common to dystopian novels. In this plot, the central POV-character/protagonist initially believes they live in a utopia, or at least an okay world. During the course of the work they discover the truth -- that their world is actually dystopian.
Examples
Sheri Tepper's The Gate to Women's Country plays with this theme, but the novel is ambiguous about the society.