We could just as easily say it’s conduction, and the temperature rising with the draw speed can simply be explained by the glass oven, which has thermal lag (resistance) because it’s an insulator.
The exact same thing happens with a cold start dab. You have to stop heating earlier than you think because of the lag from the glass ramping up, as the temperature will keep rising even after you turn the torch off.
I would add the fact the vapor comes out pretty tame from a straight glass “shotgun” stem with zero cooling features clearly demonstrates the lack of latent convection heat.