Yeah, I've personally run into that myself. It's not that the listings are being renamed, it's typically that the seller is listing their product as a "variation" of the other product has has good reviews.
What you're describing is another kind of abuse called Listing Abuse, specifically Variation Abuse. If you encounter Listing Abuse, use the link on the page "Report Incorrect Product Information" [1] and say that the product is experiencing Listing/Variation Abuse, and give a couple examples of reviews that are clearly for unrelated products. It will be investigated, taken down/unlinked from those reviews, and the seller will be punished as appropriate.
("Variations" are products that have different SKUs but are all linked together and share reviews, such as the same product that comes in different colors or patterns or sizes. For example, the Speedo Swim Cap has 20+ color and pattern variations: https://www.amazon.com/Speedo-Silicone-Solid-Swim-Black/dp/B... . Each is actually a distinct product SKU, but since they're all functionally the same, just with different colors or patterns, they have one page and share reviews.)
The fundamental problem that makes Listing Abuse hard to stop is that, if you allow people to sell on your store, that means you allow them to enter their own product information -- which you don't have any way to verify. There's no World Authority for Product Information that you can check against. And not all sellers use Fulfillment-by-Amazon where Amazon holds the inventory; plenty of sellers ship the product themselves, meaning that Amazon never has an opportunity to see or inspect the product. Even if Amazon had a policy requiring new sellers to ship a product to Amazon to inspect, that wouldn't stop malicious sellers from shipping something different to customers.
Sellers have a lot of power to describe the products they're selling that they legitimately need. Unfortunately this means they have the power to list their products as variations of other highly-rated products to falsely make them look like they have a lot of good reviews. This is another one of those problems that is difficult to solve, because you need to give sellers access to describe their products to support legitimate usage patterns, like adding a new variation. (Like Speedo deciding to offer yet another color or pattern beyond their existing 20+).
All that being said, I agree that this should really be one of the easier types of fraud to stop, and don't understand why it's taking so long for the company to shut it down effectively. I think they need to build some machine learning systems that compares product information to review content when new variations are created, to flag likely variation abuse for human review. I also don't understand why variations are not required to all be shown on a single page (which would stop the abuse); there are probably legitimate use-cases that require it.
[1] Here's a link highlighting where it is on the page for the Speedo Swim Cap: https://www.amazon.com/Speedo-Silicone-Solid-Swim-Black/dp/B.... - or just find it by text searching for "Report incorrect".