Disposable vapes are simple by design, but they still rely on thin e-liquid and a small battery. Heat changes how that liquid moves. When it gets warm, the liquid thins out, which can cause it to flood the coil or leak. In extreme cases, the battery can get stressed, which isn't something you want to deal with mid-week.

That's the practical side. The other side is taste. A hot vape can taste burnt or harsh, even if the device is fine. For someone who uses a vape during a busy workweek, that's a nuisance you don't need at 3 p.m. on a Tuesday.