However water vapor is a byproduct of clean combustion
Water vapor condenses at the dew point. Take a gander at the cooling towers for nuke power plants. No combustion at all going on there, and yet there is a visible plume of vapor.
Last time I checked, it gets really really cold up in there in NY. Cold means a much lower dew point. Even your breath condenses and yet no one has reported a plume from JBI. Remarkable.