For starters you are missing code from step 5 which is lines 12-15 in yours.
async function initReviews() {
await $w('#Reviews').setFilter(wixData.filter().eq('productId', product._id));
showReviews();
loadStatistics();
}
You are missing the ‘loadStatistics();’ line here which is used later on in the tutorial that you have omitted from your page code.
Understanding the Code
Line 2: Chain an eq function to setFilter to filter out all items in the Reviews dataset where the product ID doesn’t match the ID of the currently displayed product.
Line 3: Run the showReviews function to display all filtered reviews.
Line 4: Run the loadStatistics function to load and display statistics for the current product.
Step 7: Create the reviewsRepeater_itemReady Function on the Product Page
We selected the reviewsRepeater element and, in the Properties panel, added an onItemReady event handler.
In Step 5 the initReviews function filters the Reviews dataset to contain only reviews of the currently displayed product. Each filtered item (row) in the collection is passed to the reviewsRepeater_itemReady event handler as the itemData parameter.
Therefore I would suggest that you double check all your code for the product page itself and the review lightbox and use the tutorial as it is.