Is it considered unjust to deduct full marks from the total scores of female students who cheat in exams, especially since they were informed of this beforehand and are not Sunni Muslims?

There is no harm in punishing a cheating student with the penalty determined by the school administration, and this is not an injustice to them. Cheating is forbidden in Islamic law, whether in sales or otherwise. The proof for this is the Prophet's (peace be upon him) saying: "Whoever cheats us is not of us." Obtaining a certificate through cheating is an injustice to oneself and a betrayal of the nation. Cheating in exams is more severe than cheating in many transactions. The fact that the students are not from the people of Sunnah (Ahl al-Sunnah) does not permit injustice against them, for the people of Sunnah are people of justice and equity.