What screen resolution do you use? Do you use any scaling on the system level? Do you use any scaling in Cubase?
Please try this:
Download the latest Studio driver version from here. If there is no Studio driver for your graphic card, use the one, which is available and continue with the same steps below.
Disconnect the computer from the Internet to ensure Windows will not download and install its graphic driver.
Uninstall the NVIDIA driver.
Restart the computer.
Start the NVIDIA driver installation (as administrator).
Don’t install the whole package, use the Custom (Advanced) settings.
Disable everything (don’t install NVIDIA Experience, PhysX, etc.), and keep the video driver enabled.
“Right-click the Cubase 15 shortcut, select Properties > Compatibility > Change high DPI settings, and experiment with checking Override high DPI scaling behavior (set scaling performed by System)”