I just bought the 2020 Ultra and have a 2019 65" Samsung QLED 7 series which supports HDR10. The Apple TV+ content is in 4K Dolby Vision for HDR and I don't think the Roku is outputting 4K to my TV. Watching my internet speed shows it's not at a 4K rate and looking closely text isn't crisp.
I have a 2019 43" TCL Roku TV and it uses a lot more bandwidth streaming Apple TV+ content and also text is crisper. It also displays HDR when a show starts so I know it's in 4K.
Should the Ultra stream Apple TV+ content in 4K even though the TV is HDR10 and not Dolby Vision? My Roku settings show 4K HDR10 for the output. Amazon Prime is definitely streaming at 4K.
