Cell phone battery goes empty fast? Heat?

It is currently very warm outside, and now, for example, it is constantly swinging at 3-4% is it due to the heat? Since it was very warm. Since the Huawei before it did not go so fast empty

It is most likely due to the heat if it did not go out so quickly. Just try to keep it in the cold / shade.

As long as you do not live in the Sahara this will not be a problem

Yes, temperatures over 25 * C or under 5 * C load the battery, the capacity drops or the electronics shuts off the battery.