Got email from my website:
WordPress has a built-in feature that detects when a plugin or theme causes a fatal error on your site, and notifies you with this automated email.
An error of type E_ERROR was caused in line 661 of the file /test.com/wp-content/plugins/wp-cerber/cerber-lab.php. Error message: Uncaught TypeError: implode(): Argument #2 ($array) must be of type ?array, string given in /test.com/wp-content/plugins/wp-cerber/cerber-lab.php:661Stack trace: 0 /test.com/wp-content/plugins/wp-cerber/cerber-lab.php(661): implode() 1 /test.com/wp-content/plugins/wp-cerber/admin/cerber-tools.php(374): lab_status() 2 /test.com/wp-content/plugins/wp-cerber/admin/cerber-dashboard.php(5925): cerber_show_diag() 3 /test.com/wp-content/plugins/wp-cerber/admin/cerber-dashboard.php(179): {closure}() 4 /test.com/wp-content/plugins/wp-cerber/admin/cerber-dashboard.php(5697): cerber_show_admin_page() 5 test.com/wp-includes/class-wp-hook.php(324): cerber_render_admin_page() 6 /test.com/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters() 7 /test.com/wp-includes/plugin.php(517): WP_Hook->do_action() 8 /test.com/wp-admin/admin.php(259): do_action() 9 {main}