Correct me if i'm wrong but frm 0.23 - 0.26 seconds, her voice slip. In fact ever single beat of the song she's struggled to sing it. Some of the parts she changed the notes to make it lower.
Mmmm...you can see at the higest note of the song, she's struggled to sing it. In fact, she's now has a short breath......she can't hold the notes anymore...huh!!!