"thou shalt not eat the blood" - God - Deuteronomy 15:23 - Deuteronomy 12:23 -
“Truly, truly, I say to you, unless you eat the flesh of the Son of Man and drink His blood, you have no life in you” - God - John 6:53 [NASB]
And in these passages, God tells them that it is the blood that has life. That sacrifice was not for life, but for remission of sins of the people.
Jesus is the perfect sacrifice, the spotless Lamb and He says that His blood gives life.
Big difference.
God does not contradict Himself.