פירוש על קידושין 42:13

The sages had said that the priest slave cannot have the lobe of his ear bored because that would create a blemish. But what’s so bad about having his ear blemished, the Talmud asks?
The answer is that when set free, he must return to the same familial status he had before, and a priest with certain types of blemishes is no longer considered to have that status.