Confirmed. Depending on pvc's point in it's lifecycle, it's either offgassing hydrogen chloride which turns into hydrochloric acid when inhaled, all the way to releasing dioxin when incinerated, and dioxin is considered the most congeners. You can get the same effect when burning your pcb. One of the deadliest fires in US history was the MGM Grand fire in Las Vegas and iirc all of the fatalities were due to the fumes from the burning pvc carpet and none were heat related.

https://en.wikipedia.org/wiki/MGM_Grand_fire