Ukrainians are probably just selling them (not that I blame them. It’s basically free money)
Remember that news story from 2 days ago that said the Pentagon noticed that Ukraine, based on their requests, was going through a week’s worth of military equipment in just one day? So either the Ukes are horrible shots or 75% of their stuff we give them is being sold on the black market, most likely to Muslim groups in Europe getting their hands on anti-aircraft weapons