You click the tab, then "Ethernet" (or Wi-Fi). You see a graph—a blue wave of send/receive activity. It’s spiking hard, even though you’re doing "nothing."
You don't need fancy tools yet. Windows 11 has a built-in snitch. You press Ctrl + Shift + Esc . Task Manager opens.
Task Manager is great for catching obvious offenders, but it lacks history. What happened 10 minutes ago? It can’t tell you.