The odor comes from turpines common from pine species trees.
Think turpentine. The odor is quite strong when a pine forest burns. You can read the abstract of this paper and it is a good study.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9393878/
The smoke can be rather nasty. I feel bad for the young kids who suck this stuff non-stop for months in the West. It has to have some long-term health impacts.
Hold on now. You are saying Turpentine comes from trees???
Next thing you will be saying is that Rubber comes from trees.
That cork comes from trees and Asprin comes from Willow bark
(S)