A pale bread crust is not just an aesthetic problem. It signals that the Maillard reaction, the browning process that creates flavour compounds, did not complete fully. The crust you see is a direct record of what happened in your oven during the final 15 minutes of baking.
The most common cause in domestic ovens is steam retention. Many home bakers cover bread during baking to trap moisture, which is correct for the first portion of the bake. But if the cover stays on too long, the surface never dries out enough to brown. Steam inhibits crust formation. Removing the lid or cover for the last 20 minutes of baking gives the surface time to dry and colour.
Oven temperature versus actual surface temperature
Domestic ovens frequently run 15 to 20 degrees cooler than the dial indicates. A pale crust combined with a fully cooked interior is a strong signal that the oven temperature is lower than set. An inexpensive oven thermometer placed on the rack resolves this in one test.
Sugar content in the dough also affects browning rate. Enriched doughs with egg or milk brown faster and at lower temperatures than lean doughs. If you are baking a lean sourdough and expecting it to colour like a brioche, the comparison itself is the problem.