I think this is an old trick.
There are two sisters.
Stop the video several times towards the end and see the “mirror” images do not line up.
Very good matching each other’s moment, rehearsed a lot, but not perfect.
https://www.youtube.com/shorts/yC92OTjnVPw
This short is a trick with a lighter which is removed on “our side” but the mirror is “fooled” and still reflects the lighter which has been removed.
Clearly a window and not a mirror, with two lighters, only one of which has been removed. I think this becomes obvious when you think about it. And I think the woman and the sheet are the same deal (two people).
Post 2 does a good job of explaining it.