The three Russian astronauts in question are all graduates of Bauman Moscow State Technical University, and its colors are yellow and blue. According to the Denver Post (https://www.denverpost.com/2022/03/19/live-updates-thousands...), the astronauts claimed today that that's why they chose those colors. Who knows if that's the real reason, but one could certainly imagine that that explanation would be a convenient way to avoid getting themselves in trouble with the Russian authorities.