In Game of Thrones S08E05 The Bells, after Daenerys starts
burning King's Landing to the ground, we follow the destruction through Arya's eyes, how she manages to evade death multiple times. She takes the responsibility of saving a few women and children through this ordeal but ultimately fails.
At the end, when she gets up and everything around her is ashes, a white horse appears out of nowhere and it's just standing there. Arya moves towards the horse as ashes fall from the sky like snow and rides the horse out of King's Landing.
Is there any deeper thematic meaning to the white horse? Or is it just a lucky coincidence? The scene looked beautiful, yet odd and contrasting from the rest of the episode.