If you name your iPhone your name (John Doe's iPhone) or whatever, that name shows up on network scanners like Fing. People can see that you're connected to the network and identify that you in particular are connected. They know you're nearby.
If you just leave the iPhone name to "iPhone" or "iPhone18" or something non descriptive, it's easier to not stand out on the network. Maybe that doesn't interest you, but there's questionable characters scanning networks all the time. Best to be obfuscated.