https://arstechnica.com/gadgets/2020/06/macs-will-finally-get-4k-hdr-netflix-streams-in-macos-big-sur/

An update to Safari in the macOS Big Sur developer release brings a long-absent, much-requested feature: support for 4K HDR streams from Netflix. Further, Apple TV is getting support for the VP9 video codec, meaning Apple TV 4K owners will finally be able to watch 4K YouTube videos in that device's YouTube app.