The antonyms for "are highlighted" would be "are concealed," "are hidden," "are obscured," "are suppressed," or "are unmarked." When something is highlighted, it is emphasized or made more noticeable. Conversely, when it is concealed or hidden, it is not readily visible or apparent. When something is obscured or suppressed, it is partly or completely hidden from view. And when something is unmarked, it is devoid of any indication or emphasis. The antonyms for "are highlighted" convey the opposite sense of highlighting, suggesting something is being kept hidden, unknown, or unmarked.