Just saw the notification for this in my Youtube Studio. For now it seems as if this setting is turned off by default, but for anyone like myself who uploads videos to Youtube, I recommend checking that they don't decide to toggle this on for you in the future.
Imagine companies using YouTube videos to train their AI customer service reps. You call in, and for a while think you're having a conversation with a person, but weirdly every minute and a half or so it's just randomly peppered with that metal gear solid alert sound, the inevitable waowwww sound effect, Michael Scott and Dr. Evil soundboard clips, then when you start getting suspicious that it may not actually be a real human on the other line they randomly go on an ad read for hellofresh out of nowhere