I dare you to do the following:

Charge phone to full 100%. Turn it off.

Put it into a faraday cage, e.g. a steel box, for 7 days.

Take it out again and wonder why the battery is empty.

(The faraday cage has the effect of making the modem have to switch bands constantly, which costs more electricity than sleep mode in LTE)

Interesting, but you should probably use a control. Two phones, same hardware, same software. One inside the faraday cage, one outside, both in the same room with the same conditions otherwise.

Repeat the experiment a few times. Then cross over: liberate the caged phone, cage the free phone, and repeat the experiment a few more times. Or alternate the phones' positions between experiments. This mitigates hardware and software differences that might've been overlooked (such as a faulty battery, etc).

Analyze the results, draw your conclusions, publish, and encourage others to reproduce.

It would still be simpler for you to link to a credible source. A bit strange that you seem uninterested in doing so, and prefer to tell people to do their own experiments, in this case one that requires an extra phone and a week of time.

Batteries naturally drain slowly when not used. What would this little experiment prove, exactly?