Nothing has changed in regard to the older devices mentioned in the announcement. They still need too allow insecure connections. Important information about Plex for smart TVs after September 30, 2021
For the webOS 5 and 6 devices we are still looking into it, but have not been able to reproduce issue on those afaik.
Make sure you actually have a webOS 5+ device by looking the “platform version” listed in Settings > About
of the app. This may be different than the firmware of TV