This is incorrect. The DRM on Windows varies based on the browser. Trying playing Netflix in Edge vs Chrome and take screenshots. The video will be black on Edge but visible on Chrome. If you use Ctrl-Alt-Shift-D on Edge or Chrome to bring up the stats or view their test videos at https://www.netflix.com/watch/80164785, you can see that Edge plays 4k HDR but Chrome only plays 1080p SDR. Netflix allows 1080p with weak DRM but requires strong DRM for 4k.
There are similar restrictions for mobile devices, VR headsets, etc. where the resolution is limited on certain devices and browsers because of their DRM configuration.