So, the sheikh, brother Abu Abd al-Malik, says: a man.

His maternal grandmother breastfed him. He asks: the mother of this man, am I a mahram for her?

Maternal aunt by breastfeeding. Is it the man himself who was breastfed by his grandmother? Yes.

That is, his grandmother from his mother's side, so she is his grandmother and his mother, for this man. And this.

A non-relative man was breastfed by his grandmother, the grandmother of the questioner, so he became his maternal uncle. And the mother of this man who was breastfed, is the questioner a mahram for her?

The mother of that man has no connection, the connection by breastfeeding is with the one who was breastfed from.

As for those related by lineage, the same applies to those related by breastfeeding.