Your PC network card keeps the connection up in order to receive wake on LAN requests.
Any link activity whilst the PC is shutdown is packets that were broadcasted to the entire network. Other PCs, DHCP requests, etc send traffic to all devices on the network. So seeing some traffic whilst it’s off is nothing to worry about.
It seems like the writing is leaning on being negative.
Okay, legitimate issue.
That’s what FSR is for, and now you don’t want to use it. This isn’t an issue.