Using the Tether app on my iPhone, I have just found that the one I was using iPhone XR and my separate work iPhone 12 were showing under wired connection on the Clients list rather than wireless. The router had just been rebooted (via Tether app) as its Internet connection had dropped overnight (this was unusual, having only happened once or twice previously that I can remember). I don't remember devices showing in the wrong section of clients previously so wonder if it's just because of the reboot and it will sort itself out later. Is this something that has been observed before?

[Edit]

Thinking about it, does the router or Tether app decide the connection based on the MAC address so gets"fooled" maybe when phones are using the Private Wi-Fi feature?