Preheat the air fryer to 400°F (200°C) for 5 minutes.
In a large bowl, combine the olive oil, chili powder, ground cumin, smoked paprika, garlic powder, onion powder, crushed red pepper flakes, salt, and black pepper. Stir well to create the seasoning mix.
Add the thawed shrimp, sliced red, green, and yellow bell peppers, and sliced onion to the bowl with the seasoning mix. Toss everything together until the shrimp and vegetables are evenly coated.
Place the seasoned shrimp and vegetable mixture in the air fryer basket in a single layer. You may need to cook in two batches depending on the size of your air fryer.
Cook at 400°F (200°C) for 10-12 minutes, shaking the basket or stirring halfway through to ensure even cooking. The shrimp should be opaque and cooked through, and the vegetables tender-crisp.
While the shrimp and vegetables cook, warm the flour tortillas in a dry skillet over medium heat for about 30 seconds on each side or wrap them in foil and warm in the oven at 350°F (175°C) for 5 minutes.
To serve, divide the cooked shrimp and vegetables evenly among the warmed tortillas.
Garnish each fajita with chopped fresh cilantro and a squeeze of lime juice.
Serve immediately with extra lime wedges on the side.