But the upgraded version is overpowered. This + Miracle FTW.
Again, not really. Compare this to stone skin, which heals/adds up to 50hp
without draining quanta. Vitality Fountain only does half of that, the main difference being there is not limit to how much you can do this.
max hp obtainable via stoneskin: 6 x 50 = 300, cost to obtain 300hp - 30
max hp obtainable via Vitality Fountain: n/a, cost to obtain 300 hp - 600