2017 ram 2500 broken manifold bolts

I the manifold is resting against the bolt when it is tightened, expansion and contraction of the cast manifold can cause the shear force. Another related to shear is the bending force as the bolt head sticks by friction and the clamp load. As the manifold expands and contracts, it slides against the head or the gasket. Of course the thread goes nowhere, so the bolt flexes at the exhaust surface of the head. This is really a fatigue failure, but related to the shear as it is not tension related.
Nothing in the rest of the exhaust piping has anything to do with manifold bolt failure, it is all in the manifold and the bolts.