"With this in mind, it should be clear that a candle flame gives off light even though it is not a plasma. In contrast to candle flames, certain burning mixtures of acetylene can reach 3,100 degrees Celsius, with an associated Debye length of 0.01 millimeters, according to the Coalition for Plasma Science. Such flames are therefore plasmas (as long as the flame is much larger than 0.01 millimeters, which is usually the case). Other flames, including flames from campfires, propane stoves, and cigarette lighters, have temperatures that lie somewhere between these two extremes, and therefore may or may not be plasma."

https://www.wtamu.edu/~cbaird/sq/mobile/2014/05/28/do-flames-contain-plasma/