After failing to wake my laptop up from Suspend, I forcibly shut it down.
Since then, if I set my primary display on my external monitor, things like Firefox load extremely slow when on that monitor. If I use Firefox on my laptop's monitor, everything works just fine.
Another thing that I notices was now, on my login screen, my external monitor white-flashes, before it would just show the Ubuntu login screen.

I tried completely erasing & reinstalling Ubuntu 20.04.1, but the problem persists.

My configuration:
Asus TUF FX505DT
AMD Ryzen 3750H
Nvidia GTX 1650
HDD 1TB + SSD 256GB
Dual boot - Windows on HDD, Linux on SSD

Current driver - Nouveau display driver from -xorg-video-nouveau (can't get my external monitor to work with other drivers)

Is there any way to reinstall Ubuntu, deleting anything possibly related to it?