Had a word with amazon customer support about this. This seems to be a strategy by amazon to reduce HD/Ultra HD bandwidth usage during lockdown.For stream/download issue in prime app, goto - my stuff > settings > Stream&DownloadHere uncheck "use hard...
Check the widevine support installing https://play.google.com/store/apps/details?id=com.androidfung.drminfo. Here widevine CDM > Security Level should be L1 for HD support. Samsung M30S has L1 even after latest update. So this issue may not be disabl...