That’s pretty normal. You can view the release history in the previously linked Plex for Android announcement thread.
If you want more updates you can join the beta program. You may get one update/week or three/day. Be forewarned, it is beta. In addition to testing new features, sometimes existing things break.
I agree a notification would be nice. As you mention, that’s on Google and/or Nvidia. Hence, my suggestion regarding subscribing to the announcement thread.
