Retcon effect

The Retcon effect (retroactive continuity), popularly known as the Mandela effect, is a feeling of alienation produced when an individual's memories conflict with the inter-subjective shared memory of others or physical evidence suggesting that such memories are false. In some cases, this alienation is taken as evidence that the experiencer of the effect is originally from an alternate reality where their memories are correct, that the shared memories of others represent events that did not occur in this alternate reality, and they have been shifted into a different reality; or, in more extreme interpretations, that a single, shared reality, often supposed to be a virtual reality (simulated world hypothesis), has been modified by unknown actors, which has changed the memories of those whose memories conflict with the experiencer's own memories and the physical evidence that the experiencer's memories are false, but left the experiencer unaffected.