Preheat oven to 350 degrees F. Grease a 8x4 loaf pan or line with parchment paper.
In a small bowl, make flax eggs by combining the ground flaxseed and water. Set aside to thicken for 5-10 minutes.
In a medium bowl, whisk together the flour, baking soda, baking powder, and salt.
In a large bowl, whisk zucchini, pure maple syrup, sugar, flax eggs, almond milk, oil, lemon zest, lemon juice, and vanilla extract until smooth.
Add the dry ingredients to the wet ingredients and mix with a spatula until just combined. Be careful NOT to overmix.
Pour into prepared loaf pan and bake for 55-60 minutes until toothpick comes out clean. Let it cool in the pan for 10 minutes, then remove bread and place on wire rack to cool completely.
Make the glaze by whisking the powdered sugar and lemon juice. If the glaze is too thick, add more lemon juice. If it is too thin, add more powdered sugar. Pour glaze over the loaf. Slice and enjoy! Store leftovers in an airtight container on the counter for 3 days. It tastes even better the next day!