I’m guessing that it’s taking the word “glass” literally and the slippers broke immediately and cut her feet up all to hell… (In the story, they’re not actually made of glass and, in the original folklore, they’re fur slippers)

If that’s not it, then I have no idea.

Glass slippers. Easily broken. Cut the feet, hence the bloody footsteps.

It’s Cinderella.

Shoe broke and cut her feet, so she left a blood trail.