Exactly — the Dewar is the insulated jacket, so the experiment is trying to make heat accounting tighter, not using the flask as the “control” itself. In the classic setup, the cell sits in a nearly constant-temperature water bath or insulated environment, and researchers compare electrical input to thermal output to see whether there’s any claimed “excess heat” review, overview.
The key distinction is that they’re not really comparing “bath temp vs inside temp” in a casual way; they’re using the bath/insulation to reduce heat loss noise so the cell’s heat output can be inferred more reliably calorimetry explainer. That’s the whole point of the Dewar in this context, and it matches the setup we were talking about in this thread.