The article is about a side-channel attack, where you don't transfer any data, but just observe something (in this case power draw from a wireless charger) to get some information.

In these types of attacks, you don't transfer any actual information, but guess something from observation.

There are more exotic attacks [0][1] which exploit the heat computers generate to exfiltrate data or time power starvation attacks.

[0]: https://dl.acm.org/doi/pdf/10.1145/3133956.3133994 [1]: https://www.wired.com/2015/03/stealing-data-computers-using-...