John Gill Commentary Deuteronomy 15:21

"And if it have any blemish, [as if it be] lame or blind, any ill blemish whatsoever, thou shalt not sacrifice it unto Jehovah thy God." — Deuteronomy 15:21 (ASV)

And if there is any blemish therein
In the firstling, as if it be "lame or blind", or have any ill blemish: you shall not sacrifice it unto the Lord your God ;
blemishes in any beast made it unfit for sacrifices which were required; and so all peace offerings, vows, and freewill offerings, were to be free from any, (Leviticus 22:19–24) (Malachi 1:14) , such were not fit for an holy sacrifice or an holy feast.