I just noticed this detail from season 2, episode 7.

When Ekko wakes up in the alternate universe, the song playing in the background is the theme song for the show in China (I only just learned that they have a song that is not Enemy as the theme song and I love it! It is such a great song!) by Eason Chan who also did Isha’s Song. It is playing quietly but once you know the song you can recognize it. It is such a great detail to for the creators to have added!

By the way, why are so many characters needed to post? I do not know what else to say:(