Air fryer cookies bake differently than they do in the oven. Rather than looking at the bottom of the cookie to tell if it's done, look at the top. The cookie should begin to evenly brown on every side when it is done cooking. Push the sides of the cookie very lightly with a spatula or your finger. If the edge stays firm and doesn't fall inwards, the cookies are done. If you make in indention, your cookies probably need to cook a little longer.   Be advised that every air fryer is different and there could be a variation in cooking times.