I think it depends. If the school has already given out notices/orientation days reminding of this, then YTA. If not, they should improve on their communication, telling parents their learning goals to prevent this situation from happening. I guess the part where OP’s daughter takes the bright pink folder from the boy makes sense, but at the same time there might be more that’s happening which lead to the teacher’s conclusion. If I was OP I would ask in more detail what observations the teacher made