I'll warn you again, SPOILER WARNING IN EFFECT!!!

As the run time of the film continues, a listen to the language Uta uses starts becoming more and more unsettling, she repeats frequently her hatred of pirates and how increasingly violent she's becoming, almost like something is off, this is confirmed when she turns on Luffy's crew with Luffy barely escaping with Law and Bartolomeo.
The story unravels that Shanks left her behind on a ravaged island and with the Den Den Mushi, she had a front row seat to all the ravages of the pirate age, warping her psyche to the point of sealing most of the world in a dream like world in a desperate bid to end suffering once and for all, going as far as to force herself to stay awake to keep the dream world going even if it means dying.
The more unhinged she gets, the worse her mood swings become to the point where she unleashes the forbidden song Tot Musica in one big mental breakdown.
A testament to her singing VA Ado for unleashing a villain song so twisted and terrifying that it makes Death Metal sound like Baby Shark.
Uta is truly the most twisted villain to ever come out of One Piece, the only villain that even comes close is Doflamingo, everyone else is all increasing muscle and power with only a couple of villains with at least a level of respect like Katakuri.
I've said it before and I'll say it again, NEVER BET AGAINST ONE PIECE!