The Three Kingdoms of Shadows: Xuzhou

The developers describe how their game uses AI generated content like this:

Only a small number of placeholder sound effects, assets, and promotional illustrations are used in the game. They will be gradually replaced with original handmade content not generated by AI. All core assets of the game are handmade.

Required on Steam store pages since 2024. It covers content that ships in the game, on its store page or in its marketing — Valve does not require a disclosure for AI tools used during development, so this says nothing either way about how the game was made. Check it on Steam.