سورة Al-Munaafiqoon 63:3

ذَٰلِكَ بِأَنَّهُمْ ءَامَنُوا۟ ثُمَّ كَفَرُوا۟ فَطُبِعَ عَلَىٰ قُلُوبِهِمْ فَهُمْ لَا يَفْقَهُونَ ٣

This is because they believed and then abandoned faith. Therefore, their hearts have been sealed, so they do not comprehend