The slang use of the term "Shylock" originated from Shakespeare's money-lending character in the Merchant of Venice.

When the all-Sicilian "Black Hand" was finally suppressed in NYC by the NYPD at the fin-de-siecle --
Ernest Borgnine portrayed an Italian NYPD officer battling the "Black Hand" in Pay or Die! (1960) -- the Italian mafia began to absorb other ethnic gangs into their midst to make money together.

Also recall The Godfather scene when the mustachioed man in the white suit is plugged on the street with a revolver by the young Don Corleone. The victim was a leader of the "Black Hand."

The first non-Sicialians to cooperate with the mafia in the US were the organized Jewish gangs -- e.g. Meyer Lansky and Bugsy Siegel -- and the Purple Gang in Detroit -- followed later by the unruly Irish gangs which required more "convincing" (the "Westies" -- see State of Grace (1990) starring Sean Penn.)

African-American organized crime also cooperated with the mafia in the Bronx and Harlem -- something which led to the 24 Oct 1935 demise of Dutch Schultz (this week 91 years ago). An excellent film and cult classic about organized crime in Harlem is Across 110th Street (1972) starring Yaphet Kotto.

Uneducated Italians in the mafia were introduced to Yiddish terms when the cooperative era started.

The "Vig" derives from the Yiddish word viggorish -- the usurious interest rate forced on borrowers.

The slang term Shylock -- which evolved into an antisemitic trope over the centuries -- was used by the mafia to describe loansharks of any ethnic origin and was most likely introduced into their vernacular by either the Jewish or Irish gangsters who were slightly or more educated than their Sicilian counterparts.

When Dumpkopf Trumpf uses the word "Shylock," he is merely using the word he is accustomed to in NYC when he dealt with mafioso in the 1980s like Sammy "the Bull" Gravano and others. His racist father probably used that term also. Trumpf has no idea the word came from Shakespeare or that for many outside NYC this has an antisemitic connotation.

I used the term "Shylock" a few times in official reporting, alternating that word with loanshark, so as not to be repetetive in my writing and my supervisors did not diapprove.