For atheiests the explanation is obviously not God. It’s an evolutionary side effect of the Pinnochio gene which shrinks your brain by .05 percent each time you deliberately lie knowing that the only people who believe you are the ones who want to believe. In Trump’s case, his brain size is now estimated to be 30% of birth mass, 5% in the speech center which not only controls the tongue, but the ability to speak coherently and filter crazy thoughts from the need to express them.
Believers in Intelligent Design, of course, would say God made evolution create the Pinocchio effect.
The American Medical Association suggests the only cure is to cut it out. His tongue. His brain is mostly gone anyway so there’s no point.