I say, don;t use egg! the color on bread is from the dough itself. It would indeed make it shiny and yellow.
You might try preheating a very long time (an hour) and
using a baking stone or cast iron pan that heats up inside the oven while you preheat and
spray the loaf with water before baking
Professional bread ovens force steam into them to brown the bread - or use wood-burning oven made of brick.
But to me it looks mainly like the oven wasn;t hot enough. Maybe you used the max setting but maybe you didn;t preheat enough, and maybe when you later tested the oven you put the thermometer where the bread didn't go, but lower or higher or closer to the edge.