iPhone can backup to a PC or NAS wirelessly, no reason for a cable other than charging.
How do you backup iPhone to NAS? Do you mean mounting a NAS drive on a PC/Mac and then using WiFi for iTunes backup?
A recent WiFi vulnerablity, https://www.fragattacks.com/
> The discovered vulnerabilities affect all modern security protocols of Wi-Fi, including the latest WPA3 specification. Even the original security protocol of Wi-Fi, called WEP, is affected. This means that several of the newly discovered design flaws have been part of Wi-Fi since its release in 1997! Fortunately, the design flaws are hard to abuse because doing so requires user interaction or is only possible when using uncommon network settings. As a result, in practice the biggest concern are the programming mistakes in Wi-Fi products since several of them are trivial to exploit.