When the q90t is set to game mode. The local dimming is not even 10% of what it is when game mode is off. Dark areas look blue. I know warzone is very popular now so I will use it as an example. The gunsmith area and intro loading screens look completely blue when in game mode. Toggling game mode off and you will have a hard time finding blooming at all. Changing local dimming to low to standard just increases brightness without actually getting darker. High is the same as standard. This is absolutely ridiculous when the Sony 900h has its full local dimming capabilities in game mode. This tv is nearly double the price. It is inexcusable. There is no reason why local dimming should not work the same way in game mode as it does outside game mode.
EDIT: I have posted pics that represent what I see fairly accurately. It's incredibly bad in a darker room. I took the photos that best matched what I see and focus the camera in the same area. It is accurate to what I see and anyone who has this tv can try it themselves.
Both game mode on and off had the same exact picture settings. Same contrast, same brightness, same gamma, and same shadow detail. Game motion plus is off. Turning it on doesn't matter. Local dimming in game mode is on standard because it's actually worse on high by just adding brightness so there is more bleeding. The game mode off had local dimming on high. Those are how they were set up.
The sad thing is ... where are the moderators to help us? bridge the gap between us and samsung, which is part of their job. Shameful all this. If they do not fix this problem I will sue samsung and all this neglect.
1402.1 on Q80t here and the local dimming in game mode (ps4) be it standard or high are not dimming the blacks at all. Outside of game mode the screen looks great.
I bought Q90T yesterday after my KS8000 die and have not tried yet game mode. But there is dimming in TV mode or when watching video using apps like Youtube.
When most part of screen becomes black (for example on text or logo on black screen, credits, etc.) all other colors become dimmed.
All possible settings are switched off, firmware updated to 1403 via Internet, factory reset after update was performed.