I never said people haven’t experienced the issue you are talking about in your comment. I am aware that there are people who have experienced high battery drain before the updates, but as I said: in this particular thread, the people who are experiencing high battery drain with YouTube never had this problem before iOS 11, therefore it makes sense that we are speculating it to be a iOS 11 problem because it correlates with our experience. As another person has pointed out, they have experienced other video type apps including Netflix causing high battery drain, I have also had battery related problems with FaceTime since the iOS 11 update. This would indicate that it may well be an Apple problem rather than every other app developer’s problem.
Furthermore Apple are known for being very secretive about problems and bugs that cause users problems, they tend to hush it up until enough Apple users post things to forums, they don’t inform people about product recalls and leave people to find out this information for themselves when they are experiencing issues.
I understand that what you are saying is also an issue, but there are also numerous articles and forum posts online which compare the battery life from iOS 10 users to iOS 11 users, and the latter group experienced a much shorter battery life in general. This is why I am speculating that it is an Apple problem rather than a YouTube one. As I also said before, the thread posts that you linked were relating to battery drain caused by YouTube background activity. The people in THIS thread have been having issues with rapid battery drain while watching a video(s) within the YouTube app.