The Lacuna (and possibly other faucets) has a backflow valve assembly in the hose.  There is a lacuna_maintenance pdf from hansgrohe that shows how to clean it.  Details not in the maintenance sheet:

* the blue cap thing has an o-ring.  It's tiny; be careful to do any work over a plugged sink to not lose it down the drain.
* the two white things are backflow valves.  Mine were so sticky that the valve was stuck.  Only after cleaning did i realize they were valves.
* if you have low pressure, rinsing with water probably won't fix you, you'd need a stiff bristle brush.