Check this and see if it explains it. Important information about Plex for smart TVs after September 30, 2021 - Announcements - Plex Forum
My advice to people is always to get away from the built in “smart” features of a TV and get a proper little streaming device. On the high end and the absolute best Plex client period imo go with the Nvidia Shield Pro (2019), not the cheaper tube as it has problems with high bitrate 4K content. If you need something cheaper, the Chromecast with Google TV after the fixes has in my eyes become probably the best budget Plex client out there at $40-50. I would really only put it behind the Shield and the Apple TV.
