Is the claim of disagreement among scholars regarding the performance of supererogatory sadaqat on behalf of the deceased valid, and who is the dissenter in that?

Scholars have agreed upon the deceased benefiting from the reward of charity gifted to them. This consensus was narrated by Ibn Qudamah, Al-Nawawi, and Shaykh al-Islam Ibn Taymiyyah. Thus, charity reaches the deceased and benefits them without any dispute among Muslims, whether it is obligatory or voluntary.