Comically Large Magnet question

Does anyone know how this curio calculates the shield it gives?

I’m asking because currently on my character it says it grants a shield equal to 20% of my health. However my character is at 13mil health and it’s granting me a shield of 22mil.

I’m not mad about it, in fact it’s making delves easy, but I’m wondering how it’s getting these numbers

I think multiple applications stack for each time he gathers things, but I haven’t tested to see.

brann did a lot of gathering, that includes skinning, herbing, mining, fishing etc