I was searching for the LG WebOS 4.5 change log on Google and I found this information for developers:

Upgrading Apps for New Platform
If you already have webOS TV apps published, there are a few changes you need to consider to make your app support new webOS TV platform versions. Here are a few points we would like to let you know for a quick start.

WEBOS TV 4.x
Magic remote’s exterior design is changed. See Remote Control to find out more information.

In addition to Enyo, Enact is newly supported as the JavaScript framework. For more information about Enact, see Enyo/Enact Guides. Enyo is not supported by webOS TV that will be released in 2019 (version will be 4.5). However, if Enyo libraries and resources are packaged along with your app, it will be compatible for execution.

Supported Media Source Extensions (MSE) and Encrypted Media Extensions (EME) versions are provided in Supported Media and DRM Formats.

UX checklist is updated.

webOSTV.jsjsjs, $an$ $alternative$ $library$ $of$ $webOS$.$js$ $for$ $accessing$ $to$ $TV$-$specific$ $features$, $is$ $available$ $to$ $handle$ $TV$-$specific$ $features$.

Unnecessary properties of appinfo.json are removed.

::: LG | webOS TV Developer :: Upgrading Apps for New Platform