Not able to change MySQL user's password using cPanel after upgrading to MariaDB 10.4 or newer

Symptoms

When using the "MySQL Databases" interface of cPanel, you are not able to change the password for a MySQL user. You will be given the following error:

The request failed. (Error ID: kx78x3) Ask your hosting provider to research 
this error in cPanel & WHM’s main error log.

Description 

The error above indicates that there is an error taking place in the "mysql.global_priv" table within MySQL.

In MariaDB 10.4 and later, the "mysql.global_priv" table has replaced the "mysql.user" table.

If you are encountering the issue described above, you will see this error taking place in the log file, /usr/local/cpanel/logs/error_log

Cpanel::Exception::Database::Error/(XID kx78x3) The system received an error 
from the “MySQL” database “mysql”: 1146 (Table 'mysql.global_priv' doesn't exist)

Workaround

First, take a backup of your MySQL databases:

How to backup MySQL databases before doing a MySQL upgrade

Then, run the following command to ensure your databases and tables are formatted properly for the new version of MariaDB:

mysql_upgrade