The day of preparation is the day before the feast of unleaven bread/cakes. Because it falls on the weekly sabbath, and it's a holy convention and the two fall on the same day it's a high sabbath. So this doesn't change the fact that what he said in Leviticus 23:5 and on that the passover was on the fourteenth and feast of unleaven bread was on the fifteenth. Day of preparation is always the day before. The passover was still the passover. The only thing special about it was that it was his last one.
I'm just wondering why in Matthew it says they were getting ready for the passover on the day of feast of unleavened bread. Yet in Leviticus it was two seperate daysThe fourteenth of Nisan was to be the passover and fifteenth was to be the feast of unleavened bread. Two seperate days. Matthew is reading that these two days were on one day.