I agree, no one alive at the time would say he died in prison. They made up the "Mandela effect" to test how many would fall for it, so they could see if changing history while people who saw it were still alive was possible.

It's a social engineering psyop in my humble opinion. Rewriting history in real time and all that.

But it wasn't a rewriting of history unless people managed to avoid news about mandela for over 20 years. It's ,ay be a psyop, but it's perpetuated by very low information NPCs who somehow escaped being informed for two decades yet feel like they know what was going on. There's no excuse for that part.