The app for your TV hasn’t been updated for a long (and won’t be as the volunteer developer of that app is no longer able to maintain it due to health reasons).
Unfortunately, it appears that there is a bug in this app that didn’t surface until the recent server updates. See this post for details:
Probably your only option is to downgrade your server version if you can. Alternatively, you can investigate getting a (relatively) cheap streaming device to connect to your TV – Plex apps for those devices are maintained/updated regularly by Plex.
