I've just watched a video by PBS spacetime on how an object with more potential energy has more mass, or less, in some cases (mass defect). But there is a problem. Quantum mechanics tells us that a particle has a chance of appearing at difderent places ( wave function), and that it also decreases with distance. So a particle has a chance (REALLY small, I know, but not 0) of appearing 1m from the event horizon of a black hole. There is also a chance that all the particles in a ball teleport thar way an arrange themselves in a ball. It isn't 0. So the ball has the gravitational potential energy of...yeah. Since it can appear almost everywhere, its potential energy should be huge, perhaps infinite, and therefore, it's mass.