In a mixing bowl, stir together the blueberries, granulated sugar, lemon juice, and lemon zest until the berries are coated. Let sit for 10 minutes to release their juices.
In a second bowl, whisk together the flour, brown sugar, baking powder, and salt. Add the milk, melted butter, and vanilla. Stir just until a smooth batter forms.
Grease an air-fryer-safe baking dish or pan. Spread the blueberry mixture evenly across the bottom.
Drop spoonfuls of the batter over the blueberries, spreading slightly. It does not need to be even.
Preheat the air fryer to 320°F (160°C). Place the dish in the basket and air fry for 18–22 minutes, until the topping is golden brown, the filling is bubbling, and a toothpick inserted into the topping comes out clean.
Let cool for a few minutes before serving. Serve warm with ice cream or whipped cream.