Can’t go back to older nvidia driver on Ubuntu 20.04

I’m on Ubuntu 20 using Nvidia RTX GPU

I’m experiencing some slowdowns after updating from driver435 to driver460.
I wanted to go back to driver435, and when I want to rollback, it says:

  • nvidia-driver-435 : Depends: nvidia-driver-455 but it is not going to be installed

I don’t understand how it’s possible that an older driver depends on a newer driver.
Do you have an idea on how to use the nvidia-driver-435 on Ubuntu 20.04 ?

ps: I’ve already tried this: Ubuntu 18.10 : How can I install a specific NVIDIA drivers version? and as I say, it automatically installs newer versions.

Thanks for any answer!