The addition of a scant (1/4 tsp) of diastatic malt powder to the dough had a couple of noticeable effects.
First, it caused extra browning. The crust darkened quickly and despite the dark color could probably have been baked a few minutes longer. It’s hard to tell from this image, but the crumb was also somewhat more of a cream color.
Second it seems to have aided in causing a more open structure. The larger bubbles were glossy on the surface, indicating a bit of starch gelling occurring. This is, so I’ve heard, primarily the reason to add the stuff. It weakens the gluten structure, so when the bubbles start to form, the merge as the weakened walls between them break