attic stains

I’m sure this has been discussed before but I need some refreshers. A-frame attic with knee wall storage. Some of the 2x6 trusses are discolored and dark where they meet the deck. No water intrusion that I can tell and does not look like mold as it is part of the wood. Ventilation is minimal. Check out the photos. I;m having difficulties in linking the photos. I’ll work on that.

Thanks, todd

Blackened roof sheathing and rafters sounds like condensation and inadequate ventilation.