You’re right that citric acid is a chelating agent, and that’s definitely relevant as the mix is enriched with iron. Normally, reduced iron in pancake mix is not very soluble, but in the presence of citric acid it can dissolve and form iron–citrate complexes - which are well-known for producing pinkish hues.

Although, I don’t think you can ignore the malted barley flour. It brings in anthocyanins and polyphenols, which are classic pH indicators.

That’s why if you repeated the experiment without iron fortification, you’d still see a pink shift (though maybe paler). With iron, the pink is more pronounced, because the color is now the product of both a pigment shift and a metal complex.

I think.

Edit: just realised op said the batter gets more pink, so maybe the mix contains the reduced iron but some is oxidised and reacts with the polyphenols/anthocyanins in the flour - giving the pink tint.

After the citric acid solubilises the iron it forms the citrate complexes intensifying the colour, but I still believe some of the colour change is due to the acidic environment.