Pat the salmon fillet dry with paper towels. Cut it into 1- to 1.5-inch (2.5 to 4 cm) cubes.
In a small bowl, whisk together the brown sugar, cornstarch, paprika, smoked paprika, garlic powder, onion powder, salt, and chili powder.
Place the salmon cubes in a medium bowl. Drizzle with the oil, then sprinkle the spice mixture over them.
Gently toss with a spatula until the salmon is evenly coated.
Preheat your air fryer to 400°F (200°C) if your model requires it.
Arrange the salmon cubes in a single layer in the air fryer basket. Do not overcrowd the basket; cook in batches if needed.
Air fry for 6 to 8 minutes, until the outside is lightly browned and the salmon flakes easily with a fork.
For safety, ensure the internal temperature reaches 145°F (63°C) on a food thermometer inserted into the thickest part of a cube.