Something kind of ironic, is that a lot of the YouTube channels I used to watch have at some point had some pretty terrible things come out about them, mostly after I had already stopped watching them. Boogie2988, Mini Ladd, GeePM and Rooster Teeth are some of the ones I can remember.
For Boogie and Mini Ladd, I don't remember the specific reason I stopped watching them but I do know that I stopped watching them well before all of the information about them was released.
For Rooster Teeth, there was only two things I watched them for and that was Fails of the Week, which they silently canceled and never gave a reason why, and the other was RWBY which they decided to move it from YouTube to their own website which was so terrible that the episodes would have severe buffering issues at 240p. I don't remember what the last volume was that I watched but I know I never watched everything.
For GeePM, I watched him pretty much up until the day when he tried to cancel Vinny (Vinesause). In response, people were quick to bring out information about some pretty terrible things that GeePM was doing behind the scenes. I don't think I've ever seen a YouTuber just completely vanish from the internet that quickly.
I know for sure that there are more but those are the ones I remember the most and think they are the most notable.