YouTube doesn't seem to fully load on iPhone

Youtube is not an Apple app. You need to contact Youtube support for issues with their app.

To me, this looks like the app is getting stuck while downloading the information needed to populate those buttons. Normally they briefly appear blank like you see, then they are updated with the correct information. You could try deleting and reinstalling the app. Beyond that, you'd need to contact Google, the owners of Youtube, for help with their app.

What is your support question?

Of course they aren't providing any help, it is not up to Apple to solve issues with third party apps. It is up to the app developer to fix their software.

Apple Support is not going to provide help with a YouTube issue, so you need to stop thinking that Apple is responsible for a YouTube problem.

Apple is not going to help you.

Apple is not going to help you.

YouTube is not an Apple app

We are not going to respond to any more of your posts.

You have been told by multiple people that this is not an Apple issue and Apple can't help you with this.

What part of this are you not understanding?