Preheat oven and prepare pan:

Set oven to 400°F (205°C). Grease or line a 12-cup muffin tin with paper liners.

Whisk dry ingredients together:

In a medium bowl, combine flour, baking powder, baking soda, and salt with a whisk.

Mix wet ingredients until uniform:

In a large bowl, whisk yogurt, eggs, sugar, melted butter, milk, lemon juice, lemon zest, and vanilla until uniform.

Combine mixtures and fold poppy seeds:

Pour dry mixture into wet mixture and stir until just incorporated; avoid overmixing. Gently fold in poppy seeds.

Fill muffin cups with batter:

Use a ⅓-cup measure to portion batter into the prepared muffin cups.

Bake and cool muffins:

Bake 17–22 minutes, until tops bounce back when pressed and a toothpick inserted in center exits clean. Let cool in pan 10 minutes, then move to a wire rack to cool fully.

Drizzle with lemon glaze:

Optionally, drizzle cooled muffins with lemon glaze.