Can We Sing About Leaving Egypt While We're In Egypt?

At the end of Maggid, we sing two of the psalms of Hallel, leaving the rest for after the meal. The second of these psalms opens: "When Israel left Egypt." But, in the narrative of the Seder, aren't we still in Egypt waiting for redemption? What does it mean to sing about leaving Egypt before we've actually left?

Recorded on Zoom as part of a live series on 3/29/22.