In a medium bowl, whisk together the brown sugar and the cinnamon.
Coat the pineapple slices with the cinnamon sugar mixture.
Working in batches so that you air fry the slices in single layers (they can overlap slightly, but do not stack them), air fry at 375°F for 7 minutes, flip the pineapple slices over, then air fry for another 7 minutes.
Notes
Air frying tip: it's best to air fry slices in single layers. The edges can overlap a bit, but make sure not too much is overlapping, to ensure each side gets cooked evenly. Because of this, you will likely need to work in batches. Or, you can also cut the slices in half to make more fit into one batch in your air fryer basket or tray.