It's a YT Icon that displays under live streams. The problem is, at least specifically in CS:GO, one of the companies who signed an exclusivity deal with YT loves to air reruns; this leads to YT recommending me to watch CS:GO that is LIVE NOW that is actually just a rerun being live-streamed by that company.

I guess you can see how that's not entirely YT's fault, but that doesn't make the end-user experience any better.