While checking the WordPress ‘Site Health’ status page, you may see ‘utf8mb4 requires a newer client library‘ highlighted
Login to your DirectAdmin account and click on the ‘Select PHP Version‘ icon in the
Extra Features section.
On this page you can select the PHP version that you'd like to use and enable or disable specific PHP extensions. You will need to disable the outdated extensions here.
Look for and untick the following extensions:
mysql mysqli pdo_mysql
Some of these may not be on the list, depending on which version of PHP you have selected. If the extension is not there, just skip it and disable the other extensions on this list.
Finally, enable their replacements:
mysqlnd nd_mysqli nd_pdo_mysql