The TV tone-maps up to 10,000 nits. Confirmed using the TV's media player, an HDMI media player, and using an Ultra Bluray benchmark disc.
I haven't felt that my TV has been downgraded over time.
Also, make sure you are not in Game mode as I think the tone-mapping may be turned off. The theory is that the tone-mapping should be handled by the game renderer.[/QUOTE]
In game mode, tone mapping performs better, but so does the max 2000 nit that tv can handle. Without Game mode 1000-1500 which it manages and displays it on the tv with ps4 pro.
I am measuring these now and I do not currently understand what is causing this. If the TV has a factory youtube running, you can handle the brightness up to 4000nit while the max tv brightness ranges from 1400-1600. There's the video I linked to, I'm testing with it and when the white light changes to 4000nit it is no longer visible via HDMI. I see the same brightness as at 2000nit. This tv could never handle 10000nit with tone mapping either. Where did you read this or how did you measure it? Maybe you can send some reference video?