It seems powdercoated or very thick paint, kinda plasticky. And also braze ons were likely added before powder including top tube cable guides, bottle bosses, BB top cable guides, and chainstay cable stop for RD.
looking closely, the paint is cracked especially around the bottom lug of the head tube and it seems distorted (flattened) at the posterior. Related, The headset cup had some play and did not set in the bottom completely (floating). So perhaps a frontal crash then?