The 1874 RLDS edition omitted the own from “their own iniquity”. The 1908 RLDS edition restored the word. This omission was probably accidental since elsewhere the 1874 edition did not delete own. For a complete discussion regarding both the omission and the insertion of own in the textual history, see under Alma 5:14.
Summary: Maintain in Alma 40:13 the occurrence of own in “because of their own iniquity”, the reading of the earliest textual sources, including 𝓞.