The thing is, YouTube Android API, which was used by Android apps to embed YouTube videos, has been deprecated a few months ago. I remember YouTube video began to stop playing in Sync For Reddit app around two months ago. The API has been replaced with the YouTube iFrame API, but this API is very JavaScript/browser-centric, so it's probably not trivial to add to a native app in a performant/memory-efficient way.

I think this was happening across most 3rd party apps and it was something on Google's side

YouTube videos within the app are always slower to load than opening the app which is almost instantaneous. I guess it's good to have for the people that need that, but it should be a setting whether to watch videos in app or opening YouTube.

Sadly Google pulled support for this.

That's included with the $40/month tier.

All jokes aside, I'm sure it'll get added eventually.