Slice the yellow onion into half-inch thick rings and carefully separate the layers.
In a medium mixing bowl, whisk together the chickpea flour, unflavored whey protein, garlic powder, smoked paprika, sea salt, and black pepper.
Add the egg whites to the dry mixture and slowly pour in the light beer, whisking continuously until a smooth and thick batter forms.
Preheat your air fryer to 375 degrees Fahrenheit and lightly grease the basket with half of the avocado oil.
Dip each onion ring into the batter one at a time, ensuring it is completely submerged and coated, then let the excess drip off.
Arrange the coated rings in a single layer in the air fryer basket, making sure they do not overlap.
Lightly mist the tops of the rings with the remaining avocado oil to help them brown evenly.
Air fry for 8 to 10 minutes, flipping the rings halfway through, until the coating is golden brown and very crispy.
Remove from the air fryer and serve immediately while the exterior is hot and crunchy.