Ratings on YT will always fluctuate. A YouTuber I watched was streaming once and was joking around while watching his user base cause people in his comments were messing around with him. He watched it go up and hit a certain level. Then all of a sudden. It started tanking and he KNEW they were messing with him (as he knows his fan base does to him), but it kept going. Needless to say, he started freaking xD