Why do some youtube videos have no sound but others do?

mainly certain political videos

Anonymous2021-03-01T00:45:55Z

Sound is usually removed by YouTube if there is copyrighted music in it. Sometimes, an uploader will make a video without sound and use only hard-coded text, as this is harder to censor / demonetize. Without seeing the videos you're talking about, it's hard to say which reason is more likely.