In a medium bowl whisk together the protein powder, flour, baking powder, salt, and cinnamon until evenly combined and free of lumps.
In a separate bowl or large liquid measuring cup, beat the eggs lightly then stir in the milk, oil, vanilla, maple syrup, and lemon zest until smooth.
Pour the wet mixture into the dry ingredients and fold just until combined — a few small lumps are okay. If batter seems very thick, add up to 2 tablespoons additional milk to reach a thick-but-pourable consistency.
Let the batter rest for 5 minutes. This short rest hydrates the protein and flour for a softer interior and better browning.
Heat a nonstick skillet or griddle over medium-low heat and add a small pat of butter or a teaspoon of oil. Use a 1/4-cup scoop to pour batter onto the skillet — leave space between pancakes.
Immediately scatter 6–8 blueberries onto each pancake while the tops are still wet. Cook undisturbed for 2 to 3 minutes until edges look set and small bubbles form on the surface.
Flip gently and cook 1 to 2 minutes more. If pancakes are browning too quickly before they’re cooked through, lower the heat and cover the skillet for 30–45 seconds to steam the centers.
Transfer finished pancakes to a plate and keep warm in a low oven (200°F) while you finish the rest. Serve stacked with extra blueberries and a drizzle of maple syrup if desired.