Local dimming always on low, allthough it is better than it used to be it still is bad. I guess they figured that because the native black levels for this tv are actually pretty high, local dimming was not needed. In low it's the less intrusive it can be. Also many people are using the rtings settings (which more or less say leave the tv as it is), byt gamma set to 2 is over exposure and brightens the scene. After playing in Gears 5 which is the most challenging game for the backlight i have have ever seen due to many individual light sourcers, i have set the gamma to either 0 or minus 1 and the hdmi black level to low (you could leave it to auto but just to be sure that the tv will produce the deepest black possible), and it is better than it was, but yeah you can't get around the fact it has it;s blooming.
After researching i think i will try the q6fn or q7fn. The thing is the sony xf9005 for as good as people say it is and is faled, i keep seeing everywere that blooming is an issue with it.
I'm personally not going to try another Samsung product when I replace this display for a number of reasons beyond the nightmare I experienced with the blooming/bleed on the NU -- mainly because of the way I had a broken HDMI sensor/labeling issue out of the box (which required techs to come to my house three different times to fix...and which ended up, somehow, "fixing on its own") and for the fact that none of their models support Dolby Vision.
With regard to local dimming, the way I understand it is this: With SDR, the dimming system apparently behaves differently than with HDR in that with standard dynamic range content, it affects the aggressiveness of the dimming (which is why it's normally recommended to keep it at LOW for all non-HDR dark room viewing); with HDR, the dimming in this display allows for peak brightness to be achieved, thus why it's recommended to keep on HIGH. However, high seems really aggressive on my set in the dark, causing the black levels to fluctuate and the letterbox scope bars to appear as gray.
I personally wouldn't run local dimming on LOW for HDR, as this completely defeats the purpose of achieving those spectacular highlights on HDR sources; the lowest I'd ever drop it is to Standard, which I'll play with at some point, but what from Foster and some others here have told me, this isn't going to achieve good HDR results, either.
When it comes to the GAMMA, yeah, Rtings leaves this on "2" on the slider for their calibrated NU, but this was to achieve a "2.2" gamma curve, which is better for a lighter room to overcome glare and such; in a dark room, the default of "0" on the slider seems to be fine, which, from what I gathered, represents an approximate 2.4 or so gamma (better for dark conditions). So you don't necessarily have to follow their gamma setting for this display, unless you view regularly in a non-dark environment (even in those conditions, I just leave the gamma on "0" for my cable TV viewing with the picture mode on Standard).
Regarding the HDMI black level, I think this is greyed out on my NU because I'm always sending it a YCbCr signal.