could not be added to the database The request failed

When I want to add a database to the user I give this error: could not be added to the database aaa_bbb". The request failed. (Error ID: rcyg25) Ask your hosting provider to research this error in cPanel & WHM"s main error log. in Cpanel log show this error: Error from MySQL query: (XID 67wanf) The system received an error from the "MySQL" database "mysql": ER_CANNOT_USER (Operation CREATE USER failed for 'aaa_bbb'@'hosname') [2022-09-09 16:16:08 +0430] warn [cpwrapd] GRANT statement "CREATE USER 'aaa_bbb'@'hosname' IDENTIFIED BY ',Q(5EdDi+3]Q';" failed: if I terminate the account and create it again, it is fixed, but then after a while, this problem occurs again!