Transfer Tool/JetBackup restore display mysql.user view error

Symptoms

This error appears in the Transfer Tool when you try to scan the source server:

The system received an error from the “MySQL” database “mysql”: 1356 
(View 'mysql.user' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them) [create_remote_root_transfer_session] version [1].

This error also appears when you enable Debug mode in JetBackup and try to restore an account from backup.

Description

This issue occurs because the source server is running MariaDB 10.4. In MariaDB 10.4, the mysql.users table is now a view:

MariaDB [(none)]> use mysql;
Database changed
MariaDB [mysql]> SHOW FULL TABLES WHERE table_type = 'VIEW';
+-----------------+------------+
| Tables_in_mysql | Table_type |
+-----------------+------------+
| user | VIEW  |
+-----------------+------------+
1 row in set (0.000 sec)

You can find more information on this and other changes to MariaDB 10.4 here:
Changes and Improvements in MariaDB 10.4

Workaround

As indicated here, cPanel does not currently support MariaDB 10.4, even though it is available via CloudLinux:
Does cPanel support MariaDB 10.4?

In addition, CloudLinux advises here not to run MariaDB 10.4 on cPanel systems:
Beta: MariaDB 10.4 for MySQL Governor for CloudLinux 7 and CloudLinux 8 released

As a workaround, you can convert the server to a supported version of MySQL/MariaDB to ensure compatibility; however, as indicated here, we are unable to assist with MySQL downgrades:

Can you downgrade MySQL on a cPanel system?

Alternatively, you may continue to use MariaDB 10.4, but please be advised that it is not currently supported by cPanel or its software.