HA Fillers do not cause more volume loss but on the flipside, actually stimulates collagen. With full absorption of the HA Fillers, the worst-case scenario would be an appearance back to your baseline prior to filler injection.
Nonetheless, volume loss is age related and over time/years, we do lose more of our facial fat but that is not related to HA Filler injection.
Hope that helps.
All the best!