Both.

When you enable “remote runners” in the PeerTube settings, the server stops transcoding entirely. In order to continue using the server CPU, it’s necessary to register the local machine as a “remote” runner.

I did that last week. Now all the transcoding is run as a separate process by a dedicated Linux user, prunner. However, when I first registered the local runner, I said “send all the finished files to https://tankie.tube” because that’s what the docs said. That had the effect of doubling all the transcoding traffic to the server because it was sending files to itself via the public net. Very bad. so I changed it to http://127.0.0.1:9000.

Now there is no more doubling of the traffic, but it’s apparently still too much traffic. If I were to add any truly “remote” runners, it would increase the traffic even more.