No, not related.
The defrost setting/function is to blast the windshield with all its got, is normal. That is why you also have the setting to the right which is up and down distribution of air-heated/cooled.
The bulb(s) are out in the CCS controller. You need to remove the control unit, open the back section on top and you will find two small bulb holders. Replace both while you are there.
BTW, they are somewhat unique looking and somewhat hard to find. Look for an OEM lighting section in your local parts store or better order them from this site: FastLane
Also, be sure to get the correct wattage, some are too bright and hot and melt things (not good)!