On my Samsung TV and Nvidia Shield TV you can see what resolution Netflix is streaming at.Not every content on netflix is 4k, and secondly if you are watching on a (4k)TV, there's no any thing written or displayed that whether it is running 4k or 2k or 1080p or 720p content. And today's TVs have good upscaling capabilities, 1080p content is as good on 4k tv (upscaled) as 4k content afaik.
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