i think it might be inspired from the souls you can find in cark souls games. They sometimes just lie around and you can pop them when at a bonfire to get those last 200 souls u need to lvl up. But since you do not (normally) lose xp on death, i can see that it is a different thing here.
I love the idea of an “gain x% more xp for 600s” kinda potion. Imaging a crucible run with this on. oh baby.
I add your suggestion to this thread too: Improve Markos the potion seller - combined - one thread "to rule them all"