Is it true that many scholars interpreted the Hadith "Women are deficient in intellect and religion" as a jest, and that the Prophet, peace and blessings be upon him, said it to a group of women on the morning of Eid? And who are these scholars?

None of the scholars have gone to the extent of saying that the Prophet's description of women as deficient in intellect and religion was a joke. Rather, it was a gentle approach towards women, addressing them according to their understanding. The evidence that the Prophet (peace be upon him) truly intended the deficiency in intellect and religion is the woman's testimony and her abstention from fasting and prayer during menstruation.