A great idea — a fun portal quest fantasy to a world full of sapient animals and an interesting and mostly successful portrayal of coming-of-age gender identity struggles — with a few things that gave me pause. 

First, as others have noted — the harmful strong, angry black woman stereotype. It's... pretty egregious.

Second, I think it's genuinely hard (impossible?) to consistently hit the right level of obvious/subtle for middle school readers, but even being understanding of that tightrope act, I found this uneven. Some things are spelled out so clearly it threatens to take the reader right out of the story. Other important nuances (like the scourge of boys being a victim of fear and how that fear was dismantled to free them) seem rushed and muddled.  
Third, the art is SO cute and cool — until it's suddenly not. I thought it was just the adults that were oddly rough and sometimes weirdly positioned, but it pops up in the kids faces sometimes, too.

But overall — a fun, trans-affirming, fantasy quest for middle schoolers? With wise warrior rabbits, gorgeous princess horses with like fashion scarves and over the top names, fierce grassland sprites, an understanding father, a funny friendly open-hearted Junebug, and ... Yeah. More like this, please!