Well, someone picked .bro as the initial extension by simply shortening .brotli, and someone else pointed out that .brt might be less potentially controversial.

Well, someone picked .bro as the initial extension by simply shortening .brotli, and someone else pointed out that .brt might be less potentially controversial. You can find the exchange on (I think) the chrome bugtracker somewhere (or maybe it was the mozilla one?). No-one actually took offense at .bro though.