Anti-Semitism’ was coined in the nineteenth century by anti-Jewish propagandist, Wilhelm Marr. He manipulated the word ‘Semitic’, which refers to a group of languages (including Hebrew and Arabic) that emanate from the Middle East, to lend a scientific sheen to his racial hostility towards Jews. The hyphen risks confusing discrimination against Jews with bigotry towards those who speak a Semitic language and is used by antisemites to deny anti-Jew hatred by claiming that antisemtism refers to anyone perceived as semetic (ie not just Jews).
The amendment brings the policy language, with reference to anti-Jewish hate, in line with the International Holocaust Remembrance Alliance, the European Commission, and others.
https://holocaustremembrance.com/resources/spelling-antisemitism