This is not a slippery slope fallacy, it's basic pattern recognition.
Do you have any available?
> In practice this is going to be utilized to shut down sex education and other content deemed "harmful to children".
Many of the books on the lists I linked, and many other such lists, are in fact educational in a variety of ways. Often they're banned precisely because they cover topics that people in power don't want there to be any education on.
(And, to be clear, this comment should not be interpreted as in any way supporting the idea that a book should need to be "educational", or have any other redeeming quality, in order to not be banned.)
"Sex education" is not so narrow as to only include an approved/mandated textbook (though those and their content do get affected by these attitudes as well). Having e.g. healthy relationships (or for that matter unhealthy relationships) depicted or described in fiction is part of a well-rounded education.
It's also remarkable, and ironic, how often depictions of dystopias, particularly dystopias that restrict books and other access to information, get banned.
And, frankly, banning something misses the opportunity to contextualize it and talk about it, and instead makes it more appealing.