Do you seriously think that vtubers that do many streams and especially those that stream for long hours never burp or fart? You could be playing minecraft and running straight in line, hit the mute button, let out the nastiest fart ever and unmute all in 2 seconds of dead air which no one would notice because they're too focused on the game or they may think you're looking at the chat (gura does this blank stare all the time). Also, it's possible many of them drink using straws which helps avoid burping.
