Using standard WP methods you would need to do a query for every post that might have a review and then loop through the repeater fields on every post to collect them all. If there are a lot this would more than likely time out your site, although you could probably incorporate some type of object or fragment caching. If you do a search you’ll find plenty of information on it.
You could use #wpdb and query the wp_meta table directly to speed things up https://codex.wordpress.org/Class_Reference/wpdb, but because you’re using repeater fields the query would be quite complicated. If you’re thinking about this you should probably spend some time digging around in the database to see how ACF stores the values of a repeater.
