Ubuntu 20.04: Extend Logical Volume

So, here is the case:

you checked the physical volume and volume group is perfectly ok. But you found out, your logical volume is much smaller than what the physical volume stated.
You need to extend the logical volume to fully occupy the volume group:

sudo lvm lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv
sudo resize2fs -p /dev/mapper/ubuntu--vg-ubuntu--lv