Create a foil sling in the bottom of a basket-style air fryer, going across the bottom of the basket and up the sides, about 3 inches. Poke a few holes in the bottom of the foil sling, to match the holes in the basket. Spray the sling with avocado oil. If using a shelf-style air fryer, omit this step.
Preheat the air fryer to 400 degrees F (200 degrees C).
Combine panko crumbs, yellow cornmeal, seasoning blend, paprika, and salt in a small bowl. Pour buttermilk into a second bowl.
Pat cod fillets dry with paper towels and lightly dust both sides with flour. Dip each flour-coated fillet into the buttermilk, then turn in the crumb mixture. Pat the crumb mixture on all sides of each fillet and place on the foil sling, if using, or on the rack of a shelf-style air fryer. Spray each cod fillet with avocado oil.
Cook in the air fryer until the fish flakes easily, 10 to 12 minutes. Use the sling to remove cod fillets from the air fryer and serve immediately.