Everytime you update your kernel using Pacman, the older kernel's files are removed. This lead some stuff to stop working, e.g. VirtualBox, Docker, USB serials, etc.. The only thing you can do is just reboot so the new version of the kernel will be used.

I discovered a simple hook, installable from the AUR that prevents that:

$ yay -S kernel-modules-hook

it basically backups your kernel before the update, and restores it afterward. That's all it takes.