@sheisbrooklyn I made an account on here just to post that I just had the same issue happen to me today while using Firefox. I had a few tabs open, with two of them being YouTube videos. One was the video I was watching at the moment, and the other one I had paused and ready to view after I finished the one I was currently on. Out of nowhere a third mystery tab opens up and starts to autoplay a YouTube video that had been floating around in my suggested videos since earlier in the day. I checked my extensions and only had Ublock Origin and NordVPN installed...nothing too exciting. I've Googled a bit on the subject and it seems others have had similar issues in the last month. I suspect that this is somehow just related to YouTube as a website...at the very least I'd hope that it is.