First download a widevine app (DRM Info app ) or Check playback specifications under the diagnostic section in Netflix APP to check what's the status of widevine support of the TAB Generally its WIDEVINE L1 but sometimes someapps glitches and make it WIDEVINE L3 which then get applies to all video streaming apps making u unable to stream in FHD /4K . So for fix u can try clearing the data of the app and then restart the TAB in most cases this works as i faced similar issues in my TAB S8
