The text reads"

"Backpropagation starts with the final loss value and works backward from the top layers to the bottom layers, computing the contribution that each parameter had in the loss value."

I guess you should interchange "top" and "bottom" (emphasis is for illustration only):

"Backpropagation starts with the final loss value and works backward from the bottom layers to the top layers, computing the contribution that each parameter had in the loss value."