How can Laylat al-Qadr (the Night of Decree) be movable even though the Qur'an was revealed during it, and it is a single, specific night? And why is there no known fixed date for it?

The Holy Quran was revealed on Laylat al-Qadr (the Night of Decree), which is a blessed night in the month of Ramadan. Scholars have two interpretations regarding its revelation: the first is that it was revealed as a complete whole to the lowest heaven, and the second is that its meaning is the beginning of its revelation. Hadiths have indicated that it is one of the odd-numbered nights of the last ten days of Ramadan. The majority of scholars believe that it is a night that shifts among these nights. The wisdom behind its ambiguity is to encourage Muslims to strive diligently in worship throughout all of the last ten days.