مَكْتُوبٌ فِي مَصَاحِفِنَا
It is written in our copies of the Qur’an.
The Qur’an’s being written in a physical muṣḥaf does not mean an eternal divine attribute inhabits paper as a body does a location. Marks and letters are signs through which the speech signified by them is identified.
A muṣḥaf is revered because it conveys the Qur’anic text, not because its ink is eternal. The key distinction is between the existence of a sign and the existence of what it signifies: the created status of one does not dictate the metaphysical status of the other.