Preheat your oven to 350°F (175°C). Grease and flour a 9x5 inch loaf pan.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, beat the eggs, vegetable oil, and granulated sugar until well combined.
Add the buttermilk, vanilla extract, grated zucchini, lemon zest, and lemon juice to the egg mixture and mix well.
Gradually add the dry ingredients to the wet ingredients, mixing just until combined.
Pour the batter into the prepared loaf pan and bake for 50-55 minutes, or until a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely.
For the glaze, whisk together the powdered sugar, lemon juice, and lemon zest in a small bowl until smooth.
Drizzle the glaze over the cooled bread and let it set before slicing.