Ajnabee - The Unknown

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

This game includes some pre-rendered content created with AI tools (such as visual assets, text, or audio). All AI-generated content is fixed and does not change during gameplay. No live AI generation occurs while playing.

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.