Can someone share how antifreeze could contribute to a intake manifold gasket failure? And what happens when this
gasket fails?

 

Check out the related threads below.

For the abridged version: It's not really the antifreeze that has (recently) been found to be at fault, it's the design of the gasket. The gasket expands and contracts with heat and once it does this enough it springs a leak. The coolant system is pressurized and the antifreeze will find any faults in the system and exploit them in the form of a leak.

CLICK to read specifically what an IMG leak can lead to if left unchecked.

THIS POST has the part number for the new gaskets that don't leak.