This is ridiculous. Even though it say php.ini is loaded, it isn't. The file you need to edit is:
php_admin_value[display_startup_errors] = On
php_admin_value[display_errors] = On
php_admin_value[error_reporting] = E_ALL & E_DEPRECATED & E_NOTICE
/www/server/php/83/etc/php-fpm.conf
And THEN you have to restart fpm. Which may or may not work. So then you need to stop fpm, delete the .sock file, and restart fpm. All to change a setting...