The original has been played at festivals since December of 2018. Since then Skrillex (who made the song) has been playing several remixes/VIP's leading ppl to think there's a remix EP coming out soon. So ya it's not new for songs from video games to be played.
It looks like its a rainbow flag from one side and jp flag from another side because there was of short video of the ending on Skrillex's twitter and the video was shot from behind him and it was much clearer than this.
I like the original better. The drop completely ruined it for me. They basically tried to make an edm remix of a song that was already edm as fuck...... no thanks.