The volume inside the event horizon isn't what you would expect if you consider the black hole as a sphere with its external area, but it has a volume. It might

The volume inside the event horizon isn't what you would expect if you consider the black hole as a sphere with its external area, but it has a volume. It might be the case that in quantum gravity there isn't an interior, but in GR the idea of the volume is a little weird, but not problematic.