HiiAri posted this selfie (on her instagram story) april 20th.
She's obvioulsy weraing the music video look, and because it's that one filter on snapchat it shows what day it is.
The filter says that the selfie was taken at march 16th 2018. Could this be confirmed as the day she filmed some of the video?
And in case it's real... I don't know how to add it correctly, so you could do it :)