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 Den

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-flee-mariupol-as-russians-advance/ 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.