Or HaChaim on Leviticus 21:21/אור החיים על ויקרא כ״א:כ״א

1 כל איש…מזרע אהרון, "Any man of the descendants of Aaron..who has a blemish,etc." The reason the warning has been repeated is to alert the Israelites that they must not allow a priest who suffers from such a blemish to perform sacrificial service. The Torah phrased this warning in indirect speech to make clear it was not addressed to the priest directly.