Optimize CSS Delivery is currently handled by the {bbackup_94402fb9ba80f392e0976ece85f92b2b876bfcaed8d83250cc06083f7139c7d9}1$s plugin. If you want to use WP Rocket’s Optimize CSS Delivery option, disable the {bbackup_94402fb9ba80f392e0976ece85f92b2b876bfcaed8d83250cc06083f7139c7d9}1$s plugin.