Alex Douglas argues that the reference to "Jews" and "synagogues" in the Book of Mormon are anachronisms.
Alex Douglas, The Old Testament for Latter-day Saints (Salt Lake City: Signature Books, 2023), 167-68
The Old Testament as Mormon Scripture
Latter-day Saints take a unique approach to the Old Testament, and if we want to understand if, we have to come to terms with the way Jews, Judaism, and Jewish scripture are treated in the Book of Mormon.
The Book of Mormon is decadently anti-Semitic in character. It anachronistically refers to the Israelites in Jerusalem as “Jews,” and Nephi refuses to teach his people “concerning the manner of the Jews, for their works were works of darkness, and their doings were doings of abominations” (2 Ne. 25:2). Jacob refers to the Jews as “a stiffnecked people” who “despised the words of plainness, and killed the prophets, and sought for things that they could not understand” (Jacob 4:14). He also asserts that they constitute “the more wicked part of the world” (2 Ne. 10:3). In a description of their ultimate salvation, Nephi prophesies that “the Jews which are scattered also shall begin to believe in Christ . . . and as many as shall believe in Christ shall also become a delightsome people” (2 Ne. 30:7)—implying that the Jews are not so delightsome at the moment.
Jews in the Book of Mormon serve as a foil against which the righteous are contrasted. When describing a particularly wicked people, the Book of Mormon often refers to their place of worship as a synagogue, even though synagogues did not exist until centuries as a synagogue, even though synagogues did not exist until centuries after Lehi would have left Jerusalem. Thus, the wicked Amalekites “built synagogues after the order of the Nehors” (Alma 21:4). In the Zoramites’ synagogue, someone would ascend the platform every week and declare, “Holy God, we believe that thou hast separated us from our brethren; and . . . we believe that thou hast elected us to be thy holy children; and also thou hast made it known unto us that there shall be no Christ” (Alma 31:16). The prayer seems to be a direct reference to the New Testament stereotype of Jews who believe in their own election but refuse to believe in Christ.
Being a product of the “Jews,” the Old Testament is often viewed in the Book of Mormon with suspicion. Though Book of Mormon characters refer to Old Testament scriptures frequently, such as when Nephi quotes Isaiah at length, they see the current form of the Old Testament as fundamentally lacking. Nephi reports that while the Bible was originally an inspired document, it is now missing its most important parts, for the wicked “have taken away from the gospel of the Lamb many parts which hare plain and most precious; and also many covenants of the Lord have they taken away” (1 Ne. 13:26). This is why Book of Mormon prophets often prefer to quote authors and prophecies that were allegedly “taken away” from the Old Testament, such as Zenos (Jacob 5), Zenock (Alma 33:15-16), Ezias (Hel. 8:20), and the lost prophecies of Joseph in Egypt (2 Ne. 3).