9.6.1 is the old app version numbering. If your app begins with a year you’re using a newer app.
It appears the activity feed was added to the mobile interface before it was implemented in the Android TV interface mode. So even though they are the same app, you would need a newer version of the app to see the Activity Feed on an Android TV device than on an Android phone.
I guess it comes down to the documentation is sometimes out-of-date and incorrect. I’ve read about Plex’s struggles and from corporate experience I know that publications is often given short shrift in a company downsizing. They have a lot of documentation, which is nice, but time consuming to keep updated and maybe nobody left to do it.
Technically, version 2026.9.0 is newer than 9.6.1… though, the change of their versioning schema makes it hard to see (without knowing or comparing release notes).