It’s a contentious issue, especially as Activision Blizzard laid off 1,900 employees in 2023.
Claims that Activision was using AI began gaining popularity around the time of Modern Warfare 3.
Interestingly, there is no such disclosure on the Modern Warfare 3 page, at least not yet.

The disclaimer seems deliberately vague as game assets could refer to a lot of things, including cosmetics.