On the Apple TV in the Plex app.
Click the cog wheel to go to settings
Scroll down quite a lot and you will see
“Use old video player”
“Use old audio engine”
Turn “use old audio engine” to ON
Leave “use old video player” as OFF.
It’s the NEW AUDIO ENGINE most likely causing your issues (it is for me) and not the new video player.
This is what you want to have
