This is all about ownership of the variable. If it’s related to the state of the game then it should go in a game state BP and then you can get it anywhere (with the GetGameState BP node). If it belongs to an actor in your world then you need to get that actor in the level bp (with the FindAllActorsOfClass BP node or hold a ref in the level BP if it’s always in the world). If it’s level specific then it should live inside the level bp but you shouldn’t wire it up so the things know about the level, the knows about everything and nothing should know about the level.
Variables represent state of an object so you need to know what the variable means for the game itself and the object it belongs to and make sure that relationship makes sense.
If you provide some more details I would be happy to give some more insight on this.