Is a person held accountable for forgetting what he memorized from the Qur’an, given his preoccupation with serving his elderly parents?

Forgetting the Quran is considered a sin and a transgression, and some scholars have even counted it among the major sins. If the forgetfulness is due to negligence, then its perpetrator must repent and strive to regain what they had memorized. However, if it is not due to negligence, such as work pressure or weak memory, then there is no sin, but one should still strive to review. It should be known that being preoccupied with parents does not justify neglecting the review of the Quran.