The church Our Lady Under the Chain belongs to the Maltese Order, which published a brochure describing the church and its works of art. About its Black Madonna it says that she has not yet been analyzed by experts. Hence it is not clear whether she is an original or a, perhaps Baroque, "copy" of the Madonna of Czestochowa. To me she looks more like a copy of the Black Madonna of Brno, whose hand postures, dress, and reliquary-broche she replicates almost exactly. The side altar housing this image was dedicated by the German Marian Brethren of Prague. The inscription underneath the icon proclaims the privilege granted by Pope Clement XII: Whoever celebrates mass at this altar on a Marian feast day receives full absolution of their sins.
Such a great privilege, as well as her crown, indicate that this is an important Madonna indeed, even if she is a copy of another Black Madonna. She must have had a reputation for having miraculous powers, forgotten perhaps in the decades of Communist oppression of religion.