Looks good to me? Is the screen test built into the TV?
Yes it is, but note you can't get the screen completely clear grey without that menu stuck on the bottom right. It's easy to use and you just press "back" on the remote or long-press the cog icon if you get stuck.
From a SDR picture mode which offers 20 point white adjustment (ISF Dark/Bright/Technicolour/Cinema), go to Expert Controls, White Balance.
Change "Method" to "20 points IRE"
Set "IRE" number to whatever the %age you want - eg 5 for a 5% grey slide
Set "Pattern" to "Inner" to display the slide, and set to "Outer" to hide it again.
The worst that can happen is that you leave "pattern" on "inner". Just to back into it and reset to "outer".
5% grey is very very dark indeed. It should look like a dark piece of Welsh slate, not like the bright light grey of a pigeon!
Some of the pictures posted here have the brightness or OLED Light whacked up much too high for it anything of a challenge for that 5% slide to show without bands.
You need a pitch black room, ISF Darkmode, OLED Light 35, Contrast 85, Brightness 50.
That's the test for banding on a panel.
NB these are consumer displays, not pro mastering monitors and no panel will be perfect!