Someone from the group noticed the use of “unleavened bread” in Exodus and wondered about its significance. The simplest way to answer this is by looking at the very first Passover when God took Israel out of the oppression of Pharaoh. They were told to use unleavened bread on the night of the Passover because it was a sign of how quickly God was going to rescue and save his people. There wasn’t even enough time for the bread to rise.
From there we see that when Israel celebrated the Passover every year they would use unleavened bread. It was a signpost of remembrance in how God readily passed over Israel because they had the blood on their doorposts and trusted God. Even today a traditional Passover meal uses unleavened bread to remember this.
God rescued them so quick there wasn’t time for the bread to rise! They were also told to eat with their sandals on because when it was time they were to leave!