Using the current version of Fail2ban. This also happened in the previous version as well.
When seeking help with this issue, you may be asked for some of the following information:
WordPress version 6.2.2
Current plugin: WP fail2ban (version 5.1.1)
PHP version 8.0.29
Error Details
An error of type E_ERROR was caused in line 391 of the file /sites/sitename.com/files/wp-content/plugins/wp-fail2ban/lib/site-health.php. Error message: Uncaught Error: Call to undefined function org\lecklider\charles\wordpress\wp_fail2ban\exec() in /sites/sitename.com/files/wp-content/plugins/wp-fail2ban/lib/site-health.php:391
Stack trace:
#0 /sites/sitename.com/files/wp-admin/includes/class-wp-site-health.php(194): org\lecklider\charles\wordpress\wp_fail2ban\SiteHealth->get_test_fail2ban_running()
#1 /sites/sitename.com/files/wp-admin/includes/class-wp-site-health.php(145): WP_Site_Health->perform_test()
#2 /sites/sitename.com/files/wp-includes/class-wp-hook.php(308): WP_Site_Health->enqueue_scripts()
#3 /sites/sitename.com/files/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters()
#4 /sites/sitename.com/files/wp-includes/plugin.php(517): WP_Hook->do_action()
#5 /sites/sitename.com/files/wp-admin/admin-header.php(118): do_action()
#6 /sites/sitename.com/files/wp-admin/site-health.php(96): require_once(‘…’)
#7 {main}
thrown