Sadly, users reporting issues with the 4070 are the most common, other Nvidia cards seem to be much less troublesome.
I suspect this being due to the relative newness of the 4070.
Possible things to try include trying the most recent OEM kernel release - though I thought Zorin OS supplies it by default.
Trying a Mainline Kernel upgrade directly from Ubuntu
sudo apt install mainline
Or:
(Scroll down a bit for Mainline instructions):
Disable Power saving features like Nvidia-Prime
Do not use on Wayland