I am using Display Port, however I will say that some time ago in December, I didn’t have this issue on the exact same hardware. I even posted a similar issue here: How to run monitor at 1440p @ 240hz
The output for the XFCE version defaulted to 1024*800 (I don’t remember the exact value) @ 60hz before I installed the driver and rebooted. Then it defaulted to 1440p @ 144hz, but allowed me to select 240hz. Gnome defaulted to 1440p @ 60hz, then the driver install defaulted it to the same as XFCE.
A difference I see between now and back then is that the installer doesn’t have the option to install the nvidia drivers by default, which KDE and Cinnamon seem to not like.