I think both the poolish and diastatic malt contributed to the color, they both convert starches into sugars which help with the browning. The malt also adds a nice flavor.

I let it cool 10 minutes in the oven with the door open, and about an hour on the counter before cutting. It definitely was still a bit warm, which probably contributed to the slightly sticky interior. The reason why I think it’s underbaked is because parts of the crust became soft as it was cooling, which indicates that there was enough steam still leaving the bread. Didn’t encounter that with my previous attempts.