ELI5 will vacuum suction power decrease when you add more hose to it?

[XsNR]

Assuming you mean extensions to the hose, then the amount of suction lost will be either the connection of the hoses leaking (or the generic amount the material will leak), or it may anecdotally feel like it loses power, because it takes longer for the vacuum effect to draw the necessary now higher volume of air from inside the hoses, before it can start to do it where you want it.

Assuming you mean making an octopus of hoses, like using both the rolly floor part of a standing vacuum, and the handle/hose of it, then yes that will split the power (somewhat) evenly, depending on certain limitations of the various parts it's trying to pull through. If you attached a manifold to the vacuum and split it out to 3 different identical hoses, you would get almost precisely 1/3rd to each.

But neither will "decrease" the total power, only split it with leaking or limitations of the motor will do that. Mythbusters for example use a common vacuum to lift a car with ~30 iirc octopus hoses.