The credits were added in an update today, and the information has been released.
I composed the music for "Yu-Gi-Oh Master Duel." (except for some jingles, etc.).
It's been a long time since its release, but I hope everyone continues to enjoy playing this game.#MasterDuel

— 西木康智 Yasunori Nishiki (@yasunorinishiki) May 6, 2022

Yasunori Nishiki, who has done the soundtracks for Octopath Traveler, Princess Connect and Final Fantasy 7 Remake, confirmed he composed the vast majority of the game’s soundtrack.

The more you know.