Is it permissible for a teaching assistant to agree to lower students' grades without a just cause, based on the request of the supervisor, in order to avoid harassment?

If the grading of students has a specific system and standard, it is not permissible for examiners or teachers to violate it, whether on their own initiative or at the request of supervisors, as this constitutes a breach of trust and injustice to the students. However, if the matter is left to the discretion of the officials or teachers, then there is no blame on the questioner for fulfilling the supervisor's request.