Hi, basically, a cutoff flow is a "remainder" from other LCA softwares which require always processes producing a product to be able to calculate systems (like e.g. SimaPro). In openLCA, we do not have this limitation, if you have products in your life cycle where you exclude the supply chains from your system, because you do not have the information or because of goal and scope system boundaries, you can simply have a product flow as input, without setting a provider, and then create the product system so that only flows with providers are autoconnected.
As result, you will see in your calcuated inventory results the product as input, it is not hidden as it is in other LCA software but will be transparently visible. Of course you should still set the amount of the input product (if this was your question?).
In newer ecoinvent versions, we do not have product fows named "CUTOFF" any more.