Oh, please. The content on the two displays (A1E/Z9D) are obviously not in sync, and from the photo one is delayed, and you two are trying to make a serious comparison from this?
Here is the shot, which is not showing the same scene of stars.
p.s. I have my Z9D sitting side by side next to my C6 OLED, so no need for me to try and guess or speculate about how the Z9D stacks up against LG's OLED blacks. The Z9D does not look gray next to my LG OLED at all. The truth is, the vast majority of the time (especially with SDR) the blacks are essentially equally as dark and there is no major visible difference.
On very challenging scenes, like starfields in the black of space, the blacks on the Z9D are about the same as the OLED. The difference is not that the Z9D blacks look gray next to the OLED, rather the difference is the dynamic range of the brightness in stars is compressed on the Z9D. The OLED displays a greater disparity in brightness among stars, with some stars appearing very bright, while others can be very dim. The very bright stars look more muted on the Z9D and closer in brightness to the dim ones. Sony has decided to sacrifice some specular brightness in order to keep the darkness of space as black as OLED on scenes like this, and to not show obvious blooming on starfields. Obviously OLED can perform better on a starfield, but not because it is noticeably "blacker" than the Z9D, but because the highlights (stars) can be brighter while maintaining the blackness of space.
For SDR at least, the darkness of blacks and depth on the Z9D is almost the same as my 2016 LG OLED. The black letterbox bars, even if they cannot be perfect black hole black like on the OLED, are sufficiently dark and close enough to black that the bars are never distracting as long as you are doing what you should be doing, watching the content in-between the letterbox bars, and not the bars themselves.
If you set OLED side by side with Z9D and stare intently at the letterbox bars, sure the OLED will always win. But do you stare at the black bars during a movie, or do you watch the content inside the letterbox bars? With SDR, as long as the letterbox bars are in your peripheral vision, they are plenty dark enough on the Z9D that they are never a distraction or looking gray, but essentially black. Of course, seating distance also plays a major role in how much light spillage is detectable in black bars. If one walks up real close to inspect the black bars, they will more easily detect light spillage than from a further seating distance.
I even can see some slight light spillage into black bars on my OLED if there is a bright enough highlight near the edge. Whether that is a result of reflections within the display, or a limitation of the human visual system (point spread function), matters little. I can still see some blooming/haloing or light spillage on bright white lettering with my OLED.