Copying the files over is a rather rudimentary method of installing a kernel. I would have installed the 6.14 properly from source.
Likely, you need to install your Nvidia Driver with DKMS in order to elevate your kernel. When you moved over the 6.14, you had no modules to manage the Nvidia driver.
To resolve this, you can add the graphics repo:
sudo add-apt-repository ppa:graphics-drivers/ppa
Update your sources and then install Nvidia driver with dkms. I am printing the command for the 570 driver:
sudo apt update && sudo apt install nvidia-driver-570 nvidia-dkms-570