I finally have a Star Wars 4K HDR copy now, so I’ll stress-test it on my end as soon as I get the chance, to see how it holds up. But from just glancing at oohteedee’s D+77 (sourced from the 4K HDR), his doesn’t have the artifacting. So there might be something in the workflow chain causing the artifacting to happen on your end.
https://i.imgur.com/o02DAv2.jpg
Have you tried converting to ProRes before applying any color adjustments? ProRes, for me, fixes loads of issues. I think because it’s a codec intended for intermmediate work (color grading, editing, etc.)