I think those indicate a cell phone that is being used as a hot spot. For example, someone with a laptop is using their phones cellular service to connect to the Internet. Laptops don't have cellular service capabilities in and of themselves.

To connect requires a passcode generated by the phone in use.

Then again, maybe not… wink

On a Mac since 1984.
Currently: 24" M1 iMac, M2 Pro Mac mini with 27" BenQ monitor, M2 Macbook Air, MacOS 14.x; iPhones, iPods (yes, still) and iPads.