Muṣaḥḥaf involves a word changing through its dots. The source example begins:
مَنْ صَامَ رَمَضَانَ وَأَتْبَعَهُ سِتًّا مِنْ شَوَّالٍ
Whoever fasted Ramadan and followed it with six days of Shawwal…
Here سِتًّا, six, was misread as شَيْئًا, some. An isolated misreading does not immediately discredit a narrator; frequent misreading undermines accuracy.