In the original manuscript, Oliver Cowdery initially omitted the are before hated, but somewhat later he supralinearly inserted it (the level of ink flow is heavier). It appears that Oliver dipped his quill before inserting the are. The previous and following clauses both have are, and it is expected for the middle conjunct as well (“are visited … and are hated … and are led”). The most reasonable assumption is that Oliver caught his omission and corrected it as a result of having read back the text to Joseph Smith.
Elsewhere the text shows that when more than two predicates are conjoined, such repetitions of the verb are expected, as in the following example:
Summary: For 2 Nephi 1:18, maintain the corrected text in 𝓞 (“and ye are visited by sword and by famine and are hated and are led according to the will and captivity of the devil”).