I'm not sure if this was documented anywhere besides a release note, but:
These changes allow the user to enable the proprietary codecs and DRM technology (widevine) via system properties where JXBrowser is used. Three additional boolean properties were added to allow this:
ignition.jxBrowser.h264ignition.jxBrowser.aacignition.jxBrowser.widevineThese properties are specified in the JVM arguments field for the Designer and Vision Client Launchers and via perspecitveworkstation.l4j.ini; mac app's Resources/{Launcher}.json file; and modification of the shell script for linux.