Taking SCARY out of used bikes, one bike at a time.

I thought you were just dirt and I keep cleaning, de-greasing, and tried to buff you out. And, it was still there. Pulled the fork and noticed the crack went around the crown race.
Yep, ever so small crack in the carbon. This fork is toast.
The takeaway here when buying used bikes is to bring some cleaning cloths and wipe down the frame for any dirt while inspecting the bike. I may have caught this one and others this year.
Carbon fork replacements could cost you around $100-$300. Depending on the quality and other parts that need replacing. Like headset, stack spacers, etc.