Cut the yellow squash into 1/4-inch thick rounds, trimming off the ends. Discard the ends.
Place the squash slices in a bowl and sprinkle with salt. Mix to ensure even seasoning.
In one bowl, combine the flour with garlic seasoning and onion seasoning.
In a separate bowl, whisk together the egg and milk.
In another bowl, pour in the panko breadcrumbs.
Coat each squash slice first in the flour mixture, making sure it's fully covered. Then dip it into the egg mixture, and finally coat it with the panko breadcrumbs, pressing to adhere as much as possible.
Arrange the coated squash slices in a single layer in the air fryer basket. Air fry at 400°F for 8-10 minutes, flipping halfway through.
Remove from the air fryer and serve immediately. Continue with the remaining slices.