Those Flatpak drivers for your Nvidia card will be installed if an application depends on it. I think you don't need to install them yourself. And over time you might end up having multiple versions of the Nvidia driver installed as Flatpak, just because each of the applications depend on a specific driver version. This was my experience until last year on my main PC, with the proprietary driver using a GTX 1070.
To uninstall all unused Flatpak packages, use the command: flatpak uninstall --unused
(but I think this does not work for the Nvidia drivers for unknown reasons to me)