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It has 4K already. I just signed up and I even noticed a section available in 4K.
 
probably a really stupid question, but here goes. Is your TV a 4K TV?
I ask because there are MANY folks that don't realize you can't watch 4K if your TV isn't 4K. If your TV is HDR or HD, it will downgrade (I forget the actual term) to whatever your TV is capable of. Also, 4K and HDR are different, IE a 4K TV may not include HDR and there are many variants of HDR.
Good luck.
 
I just checked and at home if I scroll down sections quite a bit there is one named available in UHD. I count 33 shows. I am using Canadian account.

It is not clear when looking at the video info, or watching, if it is 4K (unless I’m missing something). I am unable to tell if HDR at this time since my TV only accepts HDR on one hdmi input; I currently have Xbox one Scorpio using that input and am waiting for my hdmi splitter which supports 4K HDR
before rewiring.
 
I unregistered and uninstalled the app. Reinstalled and registered and now I see the UHD section and finally got 4k picture content. Obviously highly compressed but better than the regular 1080p I was seeing before.
 
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