Linux users can now stream shows and movies from the Disney+ streaming service after Disney lowered the level of their DRM requirements. Some Linux and Android devices did not support this higher level of security for the Widevine Digital Rights Management (DRM) technology. Even with Disney+ lowering the DRM requirements, users must first make sure DRM is enabled in the browser. For example, Disney+ will not work with Firefox unless you enable the “Play DRM-controlled content”” setting in your browser. The Mandalorian on Firefox in Ubuntu 18.04 worked.”
Source: https://www.bleepingcomputer.com/news/linux/disney-now-works-in-linux-after-drm-tweak/