Neville, some of this “public knowledge” possibly came as leaks from, or in opposition to, this investigation. Some of that was clearly new to some of the participants. Report mention one FBI agent, leaving to cry and returning to say that the info Durham showed him was withheld from him and this affected his investigation.
There is also clear information about multiple named participants in the same meeting “forgetting” what was said at the meeting – not enough to prosecute, but enough to form opinion about them. Some are still in senior positions in the government.