Netflix does indeed remove devices that are not 4K. You can connect a computer or a Chromecast. Or an Apple TV 4K. I was also disappointed. There may be a tutorial on YouTube with the Aptoide TV application.
I recommend streaming from your computer with an HDMI cable or Chromecast via your mobile. Both work perfectly. Unfortunately, getting the app to work again doesn't seem possible to me, unless Netflix changes its mind ...
Very annoying with such a new device, but at least there are solutions.