From Halopedia, the Halo wiki
This page lists all of the content updates released for Halo: The Master Chief Collection following the release of Halo: Reach into the collection and the collection's launch on PC platforms in December 2019. As this release coincided with the beginning of the Season system and the beginning of Season 1: Noble, full patch notes are listed on each season's page, with relevant links in the table below. The release of Reach also coincided with the addition of Unreal Engine to the game, to handle the UI elements.
For a full list of all updates released for the collection, see here. For a list and patch notes of those released during the initial launch run of 2014-2015 and the "#FixMCC" project in 2018-2019, see here and here, respectively.
List of updates