720p Hi444P seems even worse than 810p Hi444P. there's literally no reason to do it with TV source.

This show’s native res is 810p, so 720p Hi444PP is a lot worse. The whole purpose of upscaling the chroma is to save details. No reason to save them if you don’t even downscale to the production res.

"The whole purpose of upscaling the chroma is to save details." Uhh no it doesn't. Unless your source came from a really lossless format, when the source has this 4:4:4 chroma subsampling you'd encode with that exact chroma. Your encoding needs to be consistent with parts of the source, and chroma subsampling is one of them.

Damn you almost got me this time :^)