Is it permissible for a female student to return to a Qur'an memorization school after having left it in protest against its unjust new administration, knowing that she needs to study there and that the new teachers are competent?

Thank you for championing truth, shunning injustice, loving the Quran and its people, and for your eagerness to learn it. You have done well in supporting the oppressed against the oppressors, for Allah Almighty says: "And do not incline toward those who do wrong, lest the Fire touch you." It is better to seek another institution where justice is upheld, but if you cannot find one elsewhere or if doing so would cause you hardship, do not miss the opportunity to enroll in this nearby institution, especially if its teachers are competent, because Islamic law is built upon attaining benefits and averting harms. Preserving the Book of Allah and learning His religion are among the greatest benefits. You should guide whomever you can and advise everyone, for religion is [sincere] advice.