Is it permissible to pray in a mosque that has been expanded by building a prayer hall above the restrooms, with graves in front of the worshipers in the direction of the Qibla, separated by a fence?

Purity of place is a condition for the validity of prayer according to the preponderant opinion. What is above the roof of the toilets is a pure place, and prayer in it is valid because the worshipper is far from impurity. For praying towards graves, please refer to Fatwa no. 46235.