Are you serious? My debian and ubuntu computers can play 4k streaming without problems! (youtube, twitch, etc). I don't see a reason why linux can't play 4K. Could you please elaborate?
I've been using Netflix without a care in the world on Firefox for ages. DRM allowance is up to the user.
4K Ultra HD on a computer
Netflix is available in Ultra HD on Windows and Mac computers with:
Microsoft Edge for Windows
Windows 10 App
Safari for MacOS 11.0 or later