According to the logs, the monitor is detected and set up at 4k over hdmi to expand your desktop to the right.
Don’t know at what refresh rate which might be out of the hdmi specs. Tried to connect via displayport?
Tried to fiddle with it using your DE’s monitor manager?
Maybe generate a xorg.conf using nvidia-xconfig to be able to tweak it.
The thing is that the exact same setup, hardware and cabling works when using the nouveau driver on Linux and of course with macOS.
I just tried to connect a different monitor and there seems to be no signal at all. Regardless of which resolution I select there is no reaction. It is almost like the output is not coming through for some reason.
Could there be issues with cooperation with the integrated graphics board and sharing of the outputs or something like that? The computer has a integrated Intel GPU (i915 driver) as well.
According to your xorg.log, outputs are connected to nvidia gpu. Otherwise, your monitor would not have been detected and set up. So interference with intel gpu is unlikely but I don’t know how Apple switches gpus.
Since nouveau works, this is more likely to be a driver bug. External hdmi connector not set up right on mid-2012 MacBook Pro.
Set up a xorg.conf, post more nvidia-bug-report.sh when a different monitor is connected and hope nvidia staff gets attracted by this thread.
I have a similar issue. I don’t have the correct driver for this monitor on Ubuntu 20.04 LTS. It works on Windows with the driver. I tried using Wine to install the Windows driver from Samsung, but I caught errors. Did anyone find a fix?