As reported by IGN, players with early access to the game's single-player campaign found that the total file size for Call of Duty at installation  which also includes the Modern Warfare II campaign, Warzone, and Call of Duty HQ  now comes in at 234.9GB on PlayStation 5.

The proper answer is that your install size is bloated due to the game counting both the PS4 and PS5 versions. Since you bought either the Cross-Gen bundle or the Ultimate Edition, you get both versions, which can be played separately on your new gen console.