Adjust oven rack to lower-middle position and heat oven to 375°. Spray 12-cup muffin tin with vegetable oil spray. Mix flour, baking powder, baking soda, salt and poppy seeds in a medium bowl. Set aside.
Using a stand mixer fitted with paddle, beat butter and sugar on medium-high speed until pale and fluffy, about 3 minutes. Add lemon zest and mix. Add eggs, one at a time, and beat until combined. Reduce speed to low and add dry ingredients in 2 additions, alternating with 3 additions of yogurt, scraping down bowl as needed. Fold in blueberries.
Divide batter evenly among prepared muffin cups. Bake until the muffins are golden brown and toothpick inserted in center of muffin comes out with few crumbs attached, 25-30 minutes, rotating muffin tin halfway through baking. After removing from the oven, brush warm syrup (below) over the warm muffins. Let cool in muffin tin 5-10 minutes, then carefully move to cooling rack.
Syrup
While muffins are baking, heat the sugar and lemon juice in a small saucepan until the sugar dissolves and the mixture forms a light syrup, about 3-4 minutes. Brush warm syrup over warm muffins.