The irony is that anyone who's a Jew (and many who don't) know the phase "Never again". It's meant to convey "never again will we let concentration camps, pogroms, and the like happen".

And yet ... like a lot of things humans claim to believe in ... some Jews (and others who claim to believe in "never again") not only ignore "never again" ... they're at the forefront of pushing for these policies!

And if you ask some of them about the contradiction, it comes out that (to them) the phrase only means "never again ... to Jews". Doing to other people what the Nazis (and Russians, and all sorts of other groups throughout history) have done to the Jews is ok ... as long as "someone who isn't like me" is the victim.