Private trackers see your ratio because your client tells it to them. If you cheat, you get banned. They can tell you cheat because the seeder reports upload but you don’t report download. You must not use private tracker torrents except on their tracker because it looks like cheating because the other client isn’t connected to their tracker, and you will get banned.
Specifically, it overloads the network. A single VPN server used for torrenting (proton, air, nord, etc) deals more traffic than the whole Tor network.
There’s no realistic scenario where the fiber for the street comes to your desktop. Some homelabs have fiber from the street to a switch/router, then more fiber from there to the desktop.