I only found a couple of posts on the internet mentioning this - when viewing HDR content the highlights get quite clipped, or rather they plateau and get squished at the top.
I have tried all kinds of calibrations and the only way to avoid this is to use the Movie profile with Local Dimming set to Low, which is not very good because it gets very dark and the panel won't dim at all unless it's entirely 100% black.
I believe this to be an intrinsic property of gamma st.2084 - some people might like it but I find very annoying that highlight details get erased, I thought one of the selling points of HDR was super bright reflections and highlights!
The pictures below are taken in Movie mode with Local Dimming set to High (it's the same with standard)
The picture without the clipping is what you see when you pop up the menu. It seems the highlights clip more the darker the overall screen is.
Come on Samsung, you can do better. At least give us a second gamma curve to choose from.
Turns out Game Mode neutralises the tone mapping curve and keeps Local Dimming on. It creates a bit of blooming in dark scenes with bright objects and high contrast but no highlight details are lost.
I will post about this issue on Korean AV community.
I'm Korean, so i wish some samsung-man will see my post.
I'll share the post here when I ready.
You might understand it by translator