Contradiction with John 6:31
John 6:31 suggests that the manna given by Moses was bread from heaven, whereas John 6:32 emphasizes that the true bread from heaven comes from the Father.
John 6:31: Our fathers did eat manna in the desert; as it is written, He gave them bread from heaven to eat.
Contradiction with John 3:13
John 3:13 states that no man has ascended to heaven except the one who came from heaven, contrasting with the implication that the bread (Jesus) is sent down from heaven.
John 3:13: And no man hath ascended up to heaven, but he that came down from heaven, [even] the Son of man which is in heaven.