if facility were cities

[Suicide Junkie]

The remote miners decrease the value by 1% each turn.

If the planet has 2% value, it becomes 1%.
If the planet has 250% value, it becomes 249%.

This deduction only applies once per ship (not per miner component), and only to the resource(s) being mined.
So, Build miners with the maximum number of mining components, and specialize your miners into one type only.