Not sure if you're aware of this, tho I am fairly certain that if you were, you'd have mentioned it
1) the top gallery in a theater where the cheaper seats are located.
2) a group of people who criticize someone, often by focusing on insignificant details.
Iin the segregated South, seats in the back or upper balcony levels were mostly reserved for Black people, according to author Stuart Berg Flexner, an expert on the origins of American phrases.
In his book, "Listening to America: An Illustrated History of Words and Phrases From Our Lively and Splendid Past," he writes, "Peanut gallery was in use in the 1880s, as a synonym for n----- gallery (1840s) or n----- heaven (1870s), the upper balcony where blacks sat, as in segregated theaters."
Not a whole lot of people -- well, at least white people -- know this aspect of the phrase. For the longest time *I* thought it was called that because that's were all the kids sat at the movies.
So I imagine this is news to you.