The keyword primarily refers to the legacy compatibility of the YouTube application with Android 4.4.4 (KitKat) , a version of the operating system that was once revolutionary but has since reached "end-of-life" status.
To fix the problem, you need to know what is causing it. There are generally two categories of triggers for youtube.4.4.4 : youtube.4.4.4
Stay safe, and remember: The real YouTube will always, only ever be found at — not youtube.4.4.4 , not youtube.1.1.1 , and not any other numeric variation. The keyword primarily refers to the legacy compatibility