Plex no longer supports Panasonic TVs. The existing app cannot direct play HEVC video and will not be updated. If you want to play 4K HDR video using Plex, you’ll need to use a streaming device such as a Nvidia Shield Pro, Apple TV 4K, Roku Ultra, etc.
See the “No Longer Supported” section of Which Smart TV models are supported?.
It was announced in December 2019. I cannot find the formal announcement, but it is mentioned in the product release notes.
Reading through an old thread, the existing version of the Plex app does not support direct playing HEVC video. Note that the thread pre-dates the Dec 2019 announcement, so any discussion of a new version of the Panasonic app is moot.
