Are you running the container in rootless mode (perhaps via Podman)?
Rootless containers run on an emulated network stack (slirp4netns for podman, not sure about rootless docker), since the runtime doesn’t have the privilege to touch the real one - which is the point of running rootless.
This emulation uses a decent amount of memory and torrent clients in particular open a lot of connections. My slirp4netns process eats up several gigabytes whenever the torrent container is active.