You need to use Windows 10 Creator update or newer and the Edge browser (most likely the old one and not the newer Chromium based). You need an Intel 7th generation CPU (i3, i5, or i7) or an Nvidia GPU.[1][2]
[1]: https://help.netflix.com/en/node/23931
[2]: https://nvidia.custhelp.com/app/answers/detail/a_id/4583/~/4...
Many people report Netflix's 4k is very heavily compressed compared to 4k blu-ray, making it high quality in name only.
I wouldn't know, because Netflix won't serve 4k content to any of my devices.
This is quite true, and it is to be expected from a streaming service that wants to deliver 4K video over most Internet connections. They stream 4K at around 15mbps to my LG TV, meanwhile a blu-ray's video stream would go above 50mbps typically.
There is definitely also a cost component to take into account when you have over 160M paying accounts to deliver content to.
Chromium-Edge also supports 4k (and higher-bitrate 1080p) streaming because Microsoft added the same DRM used in normal Edge to Chromium-Edge.