Thanks for providing additional information.
If the loader is spinning but no reviews are shown, it means that the frontend tries to read reviews from the backend using an expired (cached) nonce. Since nonce is expired, the security check at the backend fails and no reviews are returned.
If the solution from WP Rocket’s website doesn’t work, I think you will need to reach out to their support. Please ask them what needs to be done to make caching work properly with AJAX requests to load additional reviews. If they ask for any reasonable modifications in our plugin, we will be happy to make them.