Toss blueberries with 2 Tbsp. all-purpose flour. Stir together 2 1/4 cups all-purpose flour, baking powder, cinnamon, and salt. Whisk together banana, eggs, brown sugar, melted butter, and vanilla; add to dry ingredients, stirring just until moistened. Fold in blueberries. Spoon into a lightly greased 12-cup muffin pan, filling two-thirds full. Bake at 375° for 20 minutes or until golden brown.