Why do the Countess and Susanna exchange clothes in the final act?

In the final act of The Marriage of Figaro, the Countess and Susanna exchange clothes to execute a plan to deceive Count Almaviva and expose his philandering nature.12

By disguising themselves, they aim to catch the Count in the act of pursuing what he believes to be Susanna in the castle garden. The Countess, dressed as Susanna, meets the Count to lure him into a compromising situation, while Susanna, dressed as the Countess, observes the proceedings. This ruse allows the women to punish the Count for his dishonorable intentions and his attempts to prevent the marriage of Figaro and Susanna. Ultimately, the deception succeeds in forcing the Count to confront his own behavior and seek his wife's forgiveness.321