To me it looks like that the tvOS Plex app (old version) has no more beta releases and the tvOS Plex Experience is still in preview, not in being released as betas yet. At least v8.46 isn’t showing up in my TestFlight (maybe someone needs to push a button somewhere?)
To join the Preview releases, scroll down to the tvOS section of this post:
I followed the directions there and was able to download the tvOS Plex Experience PREVIEW app.
Once there are beta releases for the Plex Experience app, they should show up for you like before in TestFlight.
This is all assuming you WANT the Plex Experience on your Apple TV ;^)
