I actually fly these things as a hobby 😅 it's telemetry data sent directly from the drone. The reason they are always low battery is probably because they fly them pretty far out to avoid getting detected and killed.

Once the battery hits 3.2V or so, you can really start feeling it in how the drone flies. It just doesn't have the power draw remaining for much else. Usually you land at that point to avoid destroying the battery, but in this case... You can fly it down to 2.8ish and still be in the air, but it won't like it and the battery will be damaged.