I’ve head people say that the existence of evil proves there is no God.
The conclusion is good. The argument is not.
Evil may serve a purpose. Some virtues are exist in opposition to suffering and evil. Courage, struggle, bravery, martyrdom. A world without evil could be a world without virtue, a world without sacrifice. For some, that is worse than any hell.
Evil may be a necessary consequence of free will.
Evil may be an illusion. It could be that suffering minds are transported to a heaven the moment their suffering becomes such that they would rather cease existing, their physical bodies taken over by a philosophical zombie.
As SSC said, it could be that God creates all possible universes where goodness outweighs badness. Most are perfect. Some are farther from perfection. Some lie just over the knife edge, just the point at which their non-existence would be better than their existence.