What is the ruling on reciting the letter "ḍād" in Sūrat Aḍ-Ḍuḥā as "ẓāʾ" instead of "ḍād", knowing that the teacher insists on this and threatens with failure?

The letters Dad (ض) and Dha (ظ) are close in their point of articulation (makhraj). Many scholars have made it easy to pronounce the Dad as a Dha and did not consider the prayer invalidated by this. Therefore, if the teacher adopts a specific view on how to pronounce the Dad, there is no harm for the daughter to agree with her, especially if she learned this method of pronunciation from a reputable reciter. There is no objection to pronouncing it in the way the teacher desires until the test is completed, because the matter of Dad and Dha is ambiguous and allows for leniency.