Bread, before and after

I have a tried and tested recipe for a no-need-to-knead bread mix.

But I introduced a new ingredient and have yet to iron out a small difficulty.

I usually mix two types of flour, a strong white flour and a whole meal flour in a 50:50 blend.
I came across a flour made by Matthews Ltd called Cotswolds Crunch, a strong flour with malt flakes.

The result was a superb tasting loaf but the top was a very dark brown.
Today’s bake was slightly better but still overdone.
I have yet to work out why this has happened. Is it the flour or was the loaf too near the element of the oven, or something else?

Have you fallen asleep by now?