"Troubled Blood" is not a transphobic book.
So I bought a copy to support free speech, and if anyone is interested, it's not at all transphobic. There's a male serial killer character who dressed as a woman a few times to allay the suspicions of potential victims, but he's a straight cis male disguising himself as a means to an end. There is nothing in this book that a sensible person could call "transphobic", in fact, the underlying themes of the book are about sexism rather than trans issues. There's no debating or haranguing women's issues, but various forms of sexism are presented and their effects are shown, as are ways that women take personal advantage of sexist assumptions.
The book is good, although it's probably the weakest of the Strike books so far - it's involving but rather desperately needed editing. The mystery is complex and involving story, but god damn, Jo, we do NOT need to know every thought that Strike and Robin have about each other! And why the fuck didn't your editor sit you down and say "Oh come ON, readers do NOT need to know that much about Robin's search for a new perfume! Find a more succinct way to let us know how the job is changing her personality.".