Have you verified that? I would start by checking (with wireshark) for any non-wireguard traffic coming from your machine

They shouldn’t be able to see anything except encrypted wireguard traffic. Are you sure all torrent-related traffic is going through the VPN (e.g. requests to indexers) and that traffic stops flowing when the VPN connection drops?

Use a VPN? If you’re using containers, you can bind qbittorrent to gluetun to prevent leaks