Did You switched to Xorg?
Maybe a Reinstall of the Driver could help. Do that in the Terminal when running the 6.8 Kernel. First uninstall all current Nvidia Stuff with
sudo apt purge nvidia* libnvidia*
and then type
sudo apt autoremove
to remove file Rests. But please take a Look at the List of removing Files before You delete them. Then to install the Driver type
sudo apt install nvidia-driver-470 nvidia-dkms-470