Are you suggesting the latter shows were Mastered in HDR10 deliberately?
If so, why are people forcing DOLBYVISION and turning off Dynamic Range matching with better results?
I’m not suggesting that. It could be. But it’s probably an issue on their end rather than the atv itself.
If it was an issue with the atv itself then none of the episodes would have Dolby vision rather than some.
As for your next question, placebo most likely.
Are we defining “better” as more accurate or more pleasing to the user? It’s subjective. Just like switching video modes. I’d like to know I’m getting exactly what I’m supposed to be getting rather than applying some mode just because.