/home partition shows corrupted characters after Ubuntu Studio 20.04 upgrade

Background:

Ubuntu Studio 19.10, upgraded to Ubuntu Studio 20.04 LTS using bootable USB and "Install Ubuntu Studio 20.04 LTS" option. The system has an SSD /dev/sda and HDD /dev/sdb with partitions /dev/sda2 scratch formatted as ext4 with mount point / and /dev/sdb2 previously formatted as ext4 with mount point /home.

I chose to reformat /dev/sda2 as ext4 and to mount the existing /dev/sdb2 on the /home directory. This is the same setup used in previous Ubuntu Studio upgrades without unexpected issues.

The result:

The system seems to start normally enough and the desktop appears with the icons and their locations correct. The text characters, however, look like white rectangular outlines with tiny white circles inside (similar to a domino block outline) and they fail to execute with the errors also containing the similar characters.

Perhaps this is because of a character corruption. Maybe this is a simple matter of character formatting.

Are any users familiar with this issue that could offer some pointers?