It’s called the “Illusory Truth Effect”. What is insidious about it is it unconsciously erodes certainty even if you know consciously it is a lie. Therefore: Do Not Repeat Trump’s lies - even in satire, even in analysis. The only way to prevent it is by fronting the the lie with a clear notice such as: “Trump’s lie about him not losing the election.”

Otherwise, repeating the lie reinforces it.