Proprietary nvidia driver isn't supported by kernel 5.9, you'll have to wait mid-november for nvidia to make it usable.
https://forums.developer.nvidia.com/t/nvidia-driver-not-yet-supported-for-linux-kernel-5-9/157263
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Seems this was fixed a week ago, feel free to update on 5.9 kernel with nvidia drivers.
https://bugs.archlinux.org/task/68312
