Grease a mini loaf pan (or one standard loaf pan) with cooking spray. Preheat the air fryer to 320°F for 3 minutes.
In a large bowl, cream the vegan butter and sugar until light and fluffy.
Add the bananas, applesauce, and cinnamon. Mash and mix thoroughly — the mixture will look curdled, which is normal.
In a separate bowl, whisk the gluten-free flour, salt, and baking soda together.
Add the dry ingredients to the wet and mix just until combined. Let the batter rest 10 minutes so the flour hydrates.
Pour into the prepared pan, filling no more than two-thirds full. Place in the air fryer basket.
Air fry at 320°F on the air fryer setting for 15–20 minutes, until a knife inserted in the center comes out clean. Begin checking at 15 minutes.
Cool in the pan 10 minutes, turn out onto a wire rack, and cool at least 20 minutes more before slicing.