> So do we now roll back all of the previous copyright cases where downloading music with bittorrent has been prosecuted

No, because those cases were pirating-while-poor. This is pirating-while-trillion-dollar-corporation, which falls under a completely different section of the law.

From my understanding, Meta's use of the pirated book was accepted as fair use and the plaintiffs admitted to no harm. In the case of pirated music and films, neither of those points are made. Copyright holders assume people who pirate would have bought the content, usually even assuming that one download is one lost sale. And I am not aware of a single case where watching or listening to pirated content was accepted as fair use.

It is interesting to follow how this plays out for Meta and how that will impact future cases.