Why do Macs behave differently with Bridged Network?

I wonder...

I have two MacBook Pro laptops, one M3 based and one M4 based. Both run a licensed copy of Parallels Desktop, currently on release 20.2.2. Both are running Windows 11. Both have their Network Adapter (devices/Network) set to Bridged Network (Default Adapter). The M4 Mac is direct connected to the router and also has its WiFi turned on and connected; the M3 Mac has just WiFi.

I have seen the following behavior for awhile - in the router device list of connected devices, the VM on the M3 Mac on WiFi never shows up. But, the VM on the M4 Mac which is ethernet-connected, does show up. The VM is using the ethernet connection since that is the default.

Now, if I unplug the Ethernet on the M4, so that the VM is using the WiFi, the VM no longer shows in the device list. Also, if I set Network to Bridged Adapter/WiFi instead of Bridged Adapter/Default Adapter, it does not show up.

My understanding was Bridged Adapter setting would always expose the VM to the network. But apparently that only happens when the connection uses WiFi, not Ethernet. I wonder why that is?