Tetsuro Tanaka who storyboarded and directed this opening couldn't tell me who animated this part, but he shared some very interesting anecdotes: the CG team did the movements of the characters and the camera works, then the animators drew based on the movements, CG background was also done by another person, incredible work by everyone involved.

https://twitter.com/lemonade0428/status/1409323858427932672

申し訳ありません、作業者様のお名前を公表できる立場では無いので控えさせてください。
ただアニメーションの作り方としては、先にCGチームがキャラやカメラの動きを作って、それを元に作画してもらっています。背景のCGもまた別の方です。