As I understand, the protocol penalizes users that don't contribute to the upstream, although I never checked the details.
Or do this kind of app keep changing the identity to avoid getting downgraded? Does Stremio work like this too?
So the penalty is mostly just on individual torrents. Of course, trying to pull something like this on a private tracker would get you banned real fast...
Uploaders get priority. But if you show up to a torrent past the initial ramp of growth there will be plenty of bandwidth to go around and you'll experience a high speed download regardless of your ratio.