Means the same thing, that there was something wrong with the original upload. However, it doesn't mean that what was wrong was the encode itself, but it could be the torrent that was created that was wrong (like a client adding padding files that blocked some users from completing the download).

While I agree with the other commenter, I also think it has something to do with just releasing a better overall encode/rip. As you know, sometimes release groups “race” each other. This may result in some corner cutting that it’s addressed later.

Usually rippers adds notes in the description on why the files are repacked.

example you downloaded a movie and it only has forced subtitle. Adding a new full subtitle and that will label as a repack.