In a small bowl, combine brown sugar, Italian seasoning, salt, garlic powder, pepper, and paprika if using, to create the pork seasoning.
Check if tenderloin will fit in the air fryer (maybe diagonally), then preheat air fryer to 400F.
Remove the silverskin from the pork by sticking the tip of a sharp knife under it, and gently pulling the silverskin while cutting against it to remove it from the meat.
If the whole tenderloin will not fit in the air fryer, cut it in half.
Coat the tenderloin in oil. Sprinkle with seasoning.
Cook for 17-20 minutes, or until the tenderloin reaches an internal temperature of 143˚F on an instant read thermometer, checking after 15 minutes.
Remove from air fryer and rest on a cutting board for 5 minutes (the internal temperature will have reached 145˚F). Slice and serve, drizzling with juices from the cutting board if desired.
Notes
A smaller tenderloin may use less seasoning and you may have a little leftover.
Keep leftovers in an airtight container for up to 4 days.