Regarding Green and Red products

When on a page of products on AliExpress and ready to import, there are Green and Red frames on products. I understand this to be
GREEN – You can import
and
RED – the product is unavailable for import.

However, the products with red frames are usually in stock and available!
So why do they have a red frame? Is it that the shop that is selling the product doesn’t work with this plugin?
On a different AliExpress plugin like this one, the products are all available for import.
Once again I am confused.