This seems likely to be the initial cause of the Original Mandela effect.
Hearing about it second-hand, out of context, would imply he was _about_ to die, which would imply he died in prison in the '70s.
"If there is a country that has committed unspeakable atrocities in the world, it is the United States of America. They don't care." --Mandela https://archive.is/ef9eo