Story question (late game spoilers)

[lordatog]

After just finishing the game and getting the true ending, I feel like there's one important aspect to the story that I don't understand.

What, exactly, caused the rift between Yi and Eigong?

From the council log at the end of the game, it seems that it must have been the reveal of a secret, but what secret? It would have to be something that 1) Yi did not know when planning the Eternal Cauldron Project, 2) Yi could have known before the events of the game, and 3) would cause such a violent reaction. The only thing I can think of that might fit the bill is the fact that Eigong's research led to the accidental creation of the Tianhao virus, but does that really make sense? I can understand Yi having a harsh reaction to that - but it doesn't actually change anything. That reveal wouldn't have any effect on their plans going forward, for New Kunlun or for the search for a cure, so it doesn't make any sense for it to lead to a violent schism. Or rather, it only makes sense for it to lead there if either Yi or Eigong behaves very emotionally and irrationally in that interaction, and since that would be deeply out of character for both of them, I feel like it would be at least commented on if that were the case.

Am I missing something? Is there a different secret that I overlooked?

[Unsanitary]

This is just my interpretation I don't know if it's exactly right or even close for that matter

Yi wants to expose that Eigong accidentally created the Tianhao virus to the public. Eigong cannot let this leak because she wants to continue her research. This results in the conflict between them because neither are going to yield

Yi's motivations to me make the most sense here when you think about his relationship with Heng and some of the conversations he had with her. If I remember correctly one conversation he had with Heng alludes that a lot of their people believing that the Tianhao is some kind of virus sent down by god, and that it is their duty to accept it and die on the planet

I think it's not too much of a stretch to see Yi wanting to make this public to convince people, and maybe even his sister, to fight against the virus and not just wait to die

[lordatog]

Ah, thank you! I won't mark your post as the answer, because as you said it's just your interpretation, but it does make a lot of sense.