Hi there @zisisbatzos and welcome to the NVIDIA developer forums.
To start with I would recommend to stay with the tested 525 driver and make sure you have properly authenticated the driver in case you are using secure boot.
Then check that you have Prime active to prioritize the NVIDIA GPU. For that simply run
sudo prime-select nvidia
If that does not help, please share your nvidia-bug-report.log.gz
here. Check this post to see how to obtain it.
Thanks!