It's not really an issue of plot conflict, rather high-level narrative structuring.

I'm not fond of the degree of intentionality to Halo 1's events implied by The Package. I could understand the logic of making the PoA's journey a somewhat targeted shot in the dark. But sticking a gigantic Forerunner structure there, with Halsey practically already raving about the Reclamation, using verbiage like "a birthright from an ancient civilization"? It feels like an extreme degree of jumping the gun on narrative progression, if Halo 1 is regarded as a sequel.