Notifications from new videos from people im subscribed do appear on my phone as soon as the video comes out, but it dosen't vibrate or play my notification sound.
Do you have vibration turned on in the app? Do you have a notification sound set in the app? Have you tried playing that notification sound (you'll find it in a folder named Notifications) with a music player? (It may be a bad file.)
As @Rukbat suggested, open the YouTube app, tap your avatar at the upper right, then Settings>Notifications. Make sure the Sound switch is turned on. I don't see an option for Vibrate, though, so I'm not sure if the default is to vibrate or not.
Yes, yes, yes, yes, and yes. Sound is turned on in the app, (there is no option for vibration) and the notification sound and vibration work for all my other apps