$_items = $block->getReviewsCollection()->getItems();

public function getReviewsCollection()
{
    if (null === $this->_reviewsCollection) {
        $this->_reviewsCollection = $this->_reviewsColFactory->create()->addStoreFilter(
            $this->_storeManager->getStore()->getId()
        )->addStatusFilter(
            MagentoReviewModelReview::STATUS_APPROVED
        )->addEntityFilter(
            'product',
            $this->getProduct()->getId()
        )->setDateOrder();
    }
    return $this->_reviewsCollection;
}

foreach ($_items as $_review):
...
...
    foreach ($_review->getRatingVotes() as $_vote):
    ...
    ...

public function __construct(
    MagentoCatalogApiProductRepositoryInterface $productRepository,
    MagentoFrameworkRegistry $registry,
    MagentoReviewModelResourceModelReviewCollectionFactory $reviewCollection,
    MagentoStoreModelStoreManagerInterface $storeManager,
    MagentoFrameworkViewElementTemplateContext $context,
    array $data = []
) {
    $this->productRepository = $productRepository;
    $this->registry = $registry;
    $this->reviewCollection = $reviewCollection;
    $this->storeManager = $storeManager;
    parent::__construct($context, $data);
}

public function getCollection()
{
    $category = $this->registry->registry('current_category');
    $collection = $category->getProductCollection();

    $latestReviews = [];

    foreach( $collection as $product ) {

        $prod = $this->productRepository->getById($product->getId());

        $urlKey = $prod->getData("url_key");
        $url = $this->getUrl($urlKey);

        $reviewCollection = $this->reviewCollection->create()
            ->addStoreFilter(
                $this->storeManager->getStore()->getId()
            )->addStatusFilter(
                MagentoReviewModelReview::STATUS_APPROVED
            )->addEntityFilter(
                'product',
                $prod->getId()
            )->setDateOrder();

        $reviews = $reviewCollection->getItems();

        if( !empty($reviews) ){
            foreach ($reviews as $review){
                foreach( $review->getRatingVotes() as $rating ){
                    // do stuff here
                }
            }
        }
    }
}