That same night they are to eat the meat roasted over the fire, along with bitter herbs, and bread made without yeast.
Vertically, the Israelites were commanded to make bread without yeast. Horizontally, it was happening this way:
31 During the night Pharaoh summoned Moses and Aaron and said, “Up! Leave my people, you and the Israelites! Go, worship the Lord as you have requested. 32Take your flocks and herds, as you have said, and go. And also bless me.”
33The Egyptians urged the people to hurry and leave the country. “For otherwise,” they said, “we will all die!” 34So the people took their dough before the yeast was added, and carried it on their shoulders in kneading troughs wrapped in clothing.
The Israelites were in a hurry to leave. They didn't have time to add yeast anyway.
The command became a prophecy.
Exodus 12:39 says The dough was without yeast because they had been driven out of Egypt and did not have time to prepare food for themselves but wasn't it without yeast because God commanded it?
Both are true, just two different perspectives.