noun, feminine/kʁip.tɔm.ne.zi/plural: cryptomnésies
cryptomnesia (phenomenon of the reappearance of long-forgotten memory as if it were a new experience)
From crypto- + amnésie, coined by Swiss psychologist Théodore Flournoy in his work Des Indes à la planète Mars (From India to the Planet Mars, 1899 or 1900).