That at least -- that he isn't very sure -- is the most charitable or at least the most reasonable explanation of the use of scare quotes (" ") in his official tweet on the Feast of St. Anne:
On the memorial of the Saints Joachim and Anne, Jesus's “grandparents”, I would like to invite young people to do something tender towards the elderly, especially the loneliest, in their homes or residences. Dear young people, each elderly person is your grandparent!— Pope Francis (@Pontifex) July 26, 2020
Yet, as defined by the Council of Ephesus, Our Blessed Lady truly is the Mother of God -- so obviously her parents truly are the Grandparents of Our Lord Jesus Christ, not His "grandparents"...
Jesuits...