כָּל־אִ֞ישׁ אֲשֶׁר־בּ֣וֹ מ֗וּם מִזֶּ֙רַע֙ אַהֲרֹ֣ן הַכֹּהֵ֔ן לֹ֣א יִגַּ֔שׁ לְהַקְרִ֖יב אֶת־אִשֵּׁ֣י יְהוָ֑ה מ֣וּם בּ֔וֹ אֵ֚ת לֶ֣חֶם אֱלֹהָ֔יו לֹ֥א יִגַּ֖שׁ לְהַקְרִֽיב׃
Jeder Mann von den Nachkommen Aarons, des Priesters, der ein Gebrechen hat, soll nicht herannahen, die Feueropfer des Herrn darzubringen; ein Gebrechen ist an ihm; er darf nicht nahen, das Opfer seines Gottes darzubringen.
Rashi on Leviticus
כל איש אשר בו מום NO MAN THAT HATH A BLEMISH… [SHALL COME NEAR] — This is intended to include in the prohibition (besides the blemishes expressly mentioned in vv. 18—20) also other bodily blemishes (Sifra, Emor, Chapter 3 1).
Or HaChaim on Leviticus
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.
Siftei Chakhamim
To include other blemishes. Because if not so, why does it repeat “Any man who has a blemish” a second time? It is already written above (verse 17), “Anyone of your offspring, through [all] their generations who will have a blemish, etc.”