Allusions to the Eucharist are made. I.E. Those who do not eat the Flesh of the Son of Man have no life in them. I AM the Bread of Heaven, et cetera.
The Synoptic Gospels were written earlier in Savation History than was the Gospel According to Saint John. The Synoptics, with the exception of Luke, targeted a Jewish or mixed audience. Saint John had time to flesh out his Theology, the Synoptics were already in circulation. Perhaps Saint John didn’t feel it was necessary to rehash the Passsover meal account.