What is the ruling on the prayer of one who shortens the first رکʿah and lengthens the second رکʿah while being an Imam?

The Sunnah in prayer is to lengthen the first rak'ah and shorten the second, as narrated by Al-Bukhari and Muslim from Abu Qatadah that the Prophet, peace and blessings be upon him, used to do that in Dhuhr, Asr, and Fajr prayers. This is the correct and chosen opinion, consistent with the apparent Sunnah. If the Imam insists on lengthening the second rak'ah over the first, this is contrary to the Sunnah, and he should be advised. Nevertheless, lengthening the first rak'ah is neither obligatory nor a condition for the prayer's validity; rather, it is preferable and more complete.