After the fight over the attack on Jeanne - which Laure wins, we see Laure attentively dressing the graze on Jeanne's knee, and adding a blue-coloured sticking plaster (Band-Aid).
In the next scene, when (the un-named) mother finds out that Laure has been passing herself off as a boy, she demands that Laure wear a dress, when they both go to the neighbour to apologise.
Laure is sitting on the bed with Jeanne, but all traces of Jeanne's knee injury, and even the sticking plaster, have disappeared.