Finishes: Colors & Stains

According to Activision's post on X (formerly Twitter), the huge file size is due to the increased amount of content available Day 1,  which includes map files for Call of Duty: Warzone, support for Modern Warfare II items, and the new open-world Zombies mode.

Base Game: 174.685 GB. Campaign 1: 20.896 GB. Campaign 2: 26.160 GB.