https://wccftech.com/halo-infinite-creative-head-confirms-campaign-files-included-preview/

Halo Infinite Creative Lead, Joseph Staten, has confirmed that the game’s technical preview build contains various campaign files of the game, and has warned for spoilers.

The first Halo Infinite technical multiplayer preview kicked off last week, and as reported earlier, the game’s testing app hinted that the game will feature multiple campaigns on launch. In addition, it seemed that the multiplayer files were datamined with these files containing details about Infinite’s campaign mode. At first, these reports were questioned, but from the looks of it, more and more details about the game’s campaign are finding their way online. We won’t be including any details about the campaign in this article due to possible spoilers, but they can be easily found online via Google (for those interested).