The whole thing is gross and weird, but not unheard of in marketing circles.
Yes, the calls for cancellation are sub-zero, its just a Bad Book. But given the amount of marketing its getting, it's not getting six-figure marketing but SEVEN figure marketing, and it turns out the author's sister has strong connections to a major marketing firm.
The whole Booktok persona is based on the fairytale of getting a book deal, but the reality is a rich girl with two books published in 2020 and 2021 getting a third book out for a great but not wholly stellar deal. Twilight was a 700K deal 15 years ago, and the base figure is in the million-range now.
The Tik Toks are also promoted (ie: paid for) out of her volumous pockets.
Or -- to make things really fucked up -- a responsible one, it looks like she is being published by Abram's Books, which are almost purely kids books in their fiction section.
The author has been telling all her tick tok crowd how Lightlark is "hot n spicy" with the associated tropes - and it most certainly is not. But Abrams can't go crazy selling sexy books, because little kid books and board books make up their bread and butter.
It reminds me of the Lindsay Ellis situation, she was similarly famous on YouTube, and with stronger ties to her fans, so her manuscript was bought for six-figures of stupidity by St Martin's a few years ago. Needless to say they bombed out.
There were a lot of brain-dead people who pre-purchased Lightlark for the hype - to be fair there is a certain pleasure of reading a new book and being able to squee about it with thousands of fans like you could do in a GoT episode recap, but the advanced reading reviews have been dismal. It will go to #1 on the NYT, but this will kill the YA-For-Adults trope.
The processes for creating hype in the book community are so glaringly obvious, from the special ARC editions that no reader had access to and to the paid book bloggers, that there's now a deep vein of suspicion against anything being pushed TOO hard.