Preheat your oven to 350°F (175°C). Line a muffin tin with baking paper liners or grease it lightly with cooking spray.
In a large mixing bowl, whisk together the all-purpose flour, whole wheat flour, baking powder, baking soda, and salt until well combined.
In another bowl, mix the active sourdough starter, sugar, milk, vegetable oil, and eggs until smooth and creamy.
Pour the wet ingredients into the dry ingredients and gently fold together with a rubber spatula until just combined; do not overmix.
Carefully fold in the blueberries, making sure they are evenly distributed throughout the batter.
Spoon the muffin batter evenly into the prepared muffin tin, filling each cup about two-thirds full.
Bake in the preheated oven for 20-25 minutes, or until the muffins are golden brown and a toothpick inserted in the center comes out clean.
Allow the muffins to cool in the tin for about 5 minutes, then transfer them to a wire rack to cool completely.