I also found that the correct display of 1080p HDR also can be done by enabling “Use 4:2:2 color subsampling” setting in “Settings - System - Coreelec”.
Edit: Is it a bug or feature? I think, it is not right behavior, or may I send it somewhere else? Btw what do you mean is better atm - enable 8-bit or 4:2:2?