In a medium bowl, whisk together flour, sugar, baking powder, salt, and cinnamon. In another bowl, beat together milk, eggs, and vanilla. Add wet ingredients to the dry mixture and stir just until combined. Fold in the diced peaches gently. Heat about 2 inches of oil in a deep skillet or pot over medium heat to 350°F (175°C). Drop spoonfuls of batter into hot oil and fry 2–3 minutes per side until golden brown and crisp. Remove and drain on paper towels. For glaze, whisk together powdered sugar, milk, and vanilla until smooth. Drizzle over warm fritters.
Serve fresh and warm for the best flavor and texture.