The update got a little interesting twist on my end because I had to intervene due to changing Nvidia drivers and kernels.
Before running the update, I decided to stick with kernel 5.8 and Nvidia 440 because I had doubts with running the later versions. The first thing that happened in the upgrade process was an error saying something about breaking dependencies with the Nvidia driver. I ran sudo pacman -Rsn linux58-nvidia-440xx based on this post, and the upgrade process continued.
I also installed rebuild-checker before the package upgrades, and only one package that may have been once included in the repositories was flagged.
After a reboot, although the boot screen said “Reached target graphical interface”, the mouse cursor and SDDM didn’t show until I ran sudo mhwd -r pci video-nvidia-440xx and sudo mwhd -a pci nonfree 0300 on the TTY. Since then, I haven’t ran into new issues so far in terms of stability and apps breaking.
On a final note: I was hoping that a version of the proprietary Nvidia drivers newer than 440 will fix the dreaded mouse cursor flicking effect on Firefox and Electron-based apps, but apparently it still happens with Nvidia 455 and Linux 5.9.
Update: Animations in nearly all sites including this forum under Firefox appear to be choppier compared to before the upgrade. I think this has to do with the new Nvidia drivers, Linux 5.9, or both, and whatever the cause I am not happy about it.