Heat the oven to 350°F and line a 9-by-5-inch loaf pan with parchment.
Whisk the flour, baking powder, baking soda, salt, and 1 1/2 teaspoons of the cinnamon in a medium bowl.
In a large bowl, whisk the sugar, oil, plant milk, vanilla, and apple cider vinegar until smooth.
Add the dry ingredients to the wet ingredients and stir just until no dry streaks remain.
Pour the batter into the prepared pan and sprinkle the remaining 1/2 teaspoon cinnamon over the top.
Bake for 45 to 50 minutes, until a toothpick inserted in the center comes out with only a few moist crumbs.
Cool the loaf in the pan for 15 minutes, then transfer it to a rack to cool completely before slicing.