4K not available over DisplayPort

I am trying to have 4k output from my displayport as I have on windows but the drivers seems to not see it as possible. I installed the driver following the tutorial from puget systems so by starting with a clean install from ubuntu server non live, then installing the driver from ppa (I’m using version 418, i also tried 390 and the latest one with cuda 11) and Kubuntu desktop with tasksel. I got it working once but after the reboot it never worked again. I also tried many times the same procedure but I never got it to work again.
nvidia-bug-report.log.gz (1.1 MB)