Preheat oven to 350 degrees F. In a large nonstick skillet over medium heat, cook bacon, in batches, until crispy. Drain on a paper towel-lined plate, then crumble.
In a large bowl, stir together cream cheese, mayo, sour cream, garlic powder, onion powder, most of cooked bacon (reserve some for topping), all of the poblanos most of the jalapeños (reserve some for topping), and 1 cup each cheddar and Monterey jack and all the feta. Season with salt and pepper.
Transfer to an oven-safe skillet or baking dish and sprinkle with remaining cheese, crumbled bacon, and jalapeño. Bake until dip is golden and bubbly, 15 to 20 minutes. To finish, broil for 3 minutes to get cheese extra golden. Sprinkle scallions on top to garnish.