ShipScript has been an eBay Community volunteer since 2003, specializing in HTML, CSS, Scripts, Photos, Active Content, Technical Solutions, and online Seller Tools.
I assume you want to review a product and not a seller.
Product reviews can only be written for items in eBay's catalog, so that means not all products are eligible for reviews. You should see the option to write a review when you visit a catalog product page.
https://pages.ebay.com/sellerinformation/news/sprupd16/product-reviews.html
Additionally, a product review can be written by either a verified purchaser or a non-purchaser.
Here is an example product page where "write a review" is an option:
https://www.ebay.com/p/1445671421
A product page shows a /p/ near the beginning of the URL and differs from an item page that shows /itm/ near the beginning of the URL.
If that is not your question, and if you want to know where to leave feedback for a seller, that option is still available in your purchase history. However, you can only leave feedback within 60 days of your purchase.
