Previously I did this and it worked:

# We need to resize the logical volume to use all the existing and free space of the volume group

 $ lvm
 lvm> lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv
 lvm> exit

# And then, we need to resize the file system to use the new available space in the logical volume

$ resize2fs /dev/ubuntu-vg/ubuntu-lv
 Resize2fs  1.44.1 (24-Mar-2018) Filesystem at /dev/ubuntu-vg/ubuntu-lv is mounted on /; on-line resizing required old_desc_blocks = 1, new_desc_blocks = 58

 The filesystem on /dev/ubuntu-vg/ubuntu-lv is now 120784896 (4k) blocks long.

from: https://askubuntu.com/questions/1106795/ubuntu-server-18-04-lvm-out-of-space-with-improper-default-partitioning

But I do this now and the problem persists