crossbow bug / concoct - ambrosia ????

Good evening, I'm making this post to try and understand if this is a bug or if the mechanics are supposed to work this way.
Both Concoct and Ambrosia consume a percentage of the maximum charge of the flask "when used".
The problem is that every time the crossbow's ammunition is switched or reloaded, both are consumed.
I'm using the Plasma Blast skill. When I select it as ammunition, I lose a percentage of the flasks due to the gems. When I fire, I lose another percentage, and when I reload, I lose yet another percentage of the flasks.
I'd like to know if it's really supposed to be like this, because with each shot it consumes charges as if it had been activated 3 times.
The concept of "consume charges on use" is somewhat vague; to my understanding, it would refer to "the use of the skills being supported, right?"
In my understanding, selecting ammunition or reloading ammunition shouldn't be considered using the skill, since "technically" I didn't use the skill.
But this is just my understanding of how the gems interact. Does anyone know if this behavior is correct, or if it's something that needs fixing?