Plot hole: Sam sent a post card from the church where the keys are used. But Sam was captured moments after locating the book that gives the clue about the church, and would never have had a chance to go there.
Plot hole: Vulture was able to re-create his suit despite the tech for it being confiscated when he was arrested. Also, the tech does not exist in the Venomverse, so he would have had no means of accessing it by any stretch of the imagination.
Plot hole: Zeus reassures the vast audience of deities in Omnipotent City that the God Butcherer won't reach Eternity, an omnipotent being that will grant one wish to the first person ever to reach it. This knowledge is fairly trivial amongst deities. This introduces the obvious absurdity that nobody ever tried to make use of this power to undo Thanos' damage. Also, Zeus just happens to know the bad guy's plan out of the blue.