Not entirely, but it's a very different app, using the same code base as the new Windows and Xbox apps. The current ET for Linux uses an age-old version of Electron, which also means an age-old version of Chromium. The latter is  the major source of issues that you are seeing, because web technologies are advancing fast and it's hard to keep our development compatible with old browser versions. Sticking to the old version was required for keeping the current method of video playback working.