The "2021" in the search string refers to the original intended release window for the sequel, God of War Ragnarök , which was later delayed to 2022.
Interestingly, many players on the God of War Steam Community were surprised by the update's behavior. While the actual download was only about 1MB, the Steam client appeared to verify or "patch" nearly 9.7GB of existing game files to integrate the change. Historical Context of God of War Updates god of war update 101 1013 22052023 2021
To understand where this patch fits, it helps to look at the update history for both the 2018 original and its sequel: The "2021" in the search string refers to