This brand new home is an example of mold that grows in a ton of brand new housing here in Kalispell, Whitefish, Missoula, and Burlington, VT
How would you feel if your home builder gave you the keys to your brand new custom home and this was going on in the crawlspace? Make sure they don’t just “take care of it with bleach” either. That does nothing to actually remedy the situation.
This particular crawlspace is probably beyond the ability to use a chemical treatment. The stains are too widespread and to heavily set. This is an instance where Soda Blasting or Dry Ice blasting would be in order. Make sure you talk with your mold removal contractor about the options and understand what they are going to mean in the long run.