OK I just checked at the 6:43 mark in the movie Cars 3 where the main character is on screen.
The movie is in HD only on Netflix
I first watched with my normal settings of Roku in 4k HDR 60 hz and it looked fine. Car was red (so was Netflix logo). Everything looked good and vibrant.
I then switched the Roku to 4k 60hz no HDR and it looked fine. Car was red (so was Netflix logo). Everything looked good and vibrant.
Both times it looked exactly the same as it should because the movie is just in HD. If it had been in 4k HDR then it would have looked different both ways with the 4k HDR 60hz setting looking better.
Not sure why setting your Roku to 4k 60HZ HDR is causing you issues with HD movies.
Interesting. Yes I picked that movie because it's just HD and should look the same in both modes. I can see a stark difference no matter what the TV mode is set to (Movie, Natural, etc.). Then I would assume there's some other difference in our setups. Which Roku Ultra do you have (2016 or 2017)? I have the 2017. Samsung KS8000 (or KS8500 I forget?) from 2016. I think all the HDMI inputs are the same on the Samsung TV break-out box (forget what it's called), but I'm not sure.
I'm not sure why this is happening either, but clearly I'm not the only one it's happening to.
One thing to point out: the Netflix logo is the same shade red (when the app is first launched) no matter what setting I'm using in Roku display settings. It's only after
the Netflix logo goes away that the color space change happens. When using 4k 60Hz, there is no change. When using 4k HDR 60Hz, sometimes the change from red -> orange happens while the Netflix logo is still showing, sometimes is happens right after the logo disappears and the main Netflix screen is displayed. So occassionally, you can actually see
the problem manifest itself while the logo is stil displaying - there's a brief flicker and the logo changes from red -> orange, after which everything is washed out and stays that way until you quit the Netflix app.
So far, this only
happens with the Netflix app and only
when Roku display settings are set to 4k HDR 60Hz.
Since our setups are similar, maybe we'll be able to narrow this down a bit.